Visit the Adult book store video arcade, go in a booth, turn on a gay video, turn up the volume so others can hear, strip naked except your shoes, forget to lock the door, sit on the stool facing the door slowly stroking your cock, hoping somebody will walk in on you, or get on your knees on the floor so the guys in the 3 booths across the aisle can look under the cutoff doors to watch you while they jerk off, and you don't even care if you get off, as long as you get at least a couple cocks to fill your mouth with cummmm or to blow all over your face and chest before you run out of quarters or tokens and time and have to get back home to the little woman. Or at least you know you're bi.

your fucking your girl friend and the only way you can stay hard is thinking about fucking her brother

Just reading this question makes my cock start rising. I guess that answers that question!

....you get lots of "straight" married men asking u to cam with them

Lots of good ones listed above.
Here's a few more: (I admit, I stole this list from another site ... link at the end.)

In case you didn't know it, here are a bunch of ways to tell if you're gay. Maybe you are, maybe you're not - we don't really care (freedom of expression right?). This is more of a guide. If at least 5 of these things describe you, you just might be a homosexual. Congrats.

1. You could care less who Brittany Spears is sleeping with.
2. You understand the differences between 27 brands of imported chardonnay.
3. You can call anyone "honey" including pets.
4. You know someone who was in the emergency room with Richard Gere the gerbil.
5. You understand the immense importance of quality lighting.
6. You can be at a crowded disco the size of a baseball field and still spot a toupee.
7. You can tell a woman you love her bathing suit, and truly mean her bathing suit.
8. You can explain the nuances between steady date, boyfriend and lover.
9. You really have "Been there, Done that."
10. Your women friends will tell you everything you want to know about their boyfriends.
11. You're the only type of male who gets to say "fabulous."
12. You can have naked pictures of men you don't know in your house.
13. You can have naked men you don't know at your house.
14. You know how to handle the telephone like a Stradivarius.
15. You understand why God invented spandex.
16. You understand why God didn't intend everyone to wear it.
17. You know how to get back at just about everyone. And have.
18. You know that the most important part of a party's decor is the catering staff.
19. You only wear polyester when you mean to.
20. You can smile to let someone know you hate them.
21. You can freeze a troll from 20 feet away.
22. You're good pals with women other people can't stand.
23. You've always got an opinion.
24. You've read the book, seen the movie, done the musical.
25. You know how to dress strategically.
26. Your car has an amusing female name.
27. You're the only one at your reunion who looks better than you did in high school.
28. You've got at least one framed picture of your cat.
29. If your mattress could talk, it would be Madonna.
30. You know that sex complicates things. So?
31. You know that being called a "cheap slut" isn't actually an insult.
32. There's a married guy somewhere who is terrified of you.
33. Nobody tells you what to do in bed...unless you tell them what to tell you.
34. You have a medicine chest stocked for any occasion.
35. You have at least one movie musical on video.
36. You're not embarrassed to sing in a piano bar.
37. You're embarrassed by people who sing in piano bars.
38. You never hold a grudge for longer than a decade or two.
39. You know how to make an entrance.
40. You know when to make an exit.
41. You worry about people you don't even know - like Elton John.
42. You choose the most fabulous greeting cards.
43. You know how to program your VCR.
44. You've got sunscreen at every conceivable SPF level.
45. You have a cologne display worthy of Bloomingdales.
46. You understand, viscerally, Joan Crawford.
47. Some of your best friends are your ex lovers.
48. You know when to play dumb.
49. You know what to do for a hangover.
50. Yes, you do have a condom.
51. You've called someone "girlfriend" who is neither a girl nor a friend.
52. One or more of the following apply to you:
a) You adore Famke Janssen
b) You hate Famke Janssen
c) You hate people who adore Famke Janssen .
d) You hate people who hate Famke Janssen .
e) You don't give a damn about Famke Janssen .
f) Who is Famke Janssen ?
53. You can supply the last names to the following list:
a) Bernadette
b) Chita
c) Barbra
54. You made Donna Summer a star.
55. You made Donna Summer a has-been.
56. Tanning salons were invented for you.
57. You've made sunbathing a performance art.
58. You know when the party's over.
59. You know where to go after the party's over.
60. You're fearless about fighting the elements, especially gravity.
61. When you hear "a stitch in time saves nine" you think of
a) Your grandma
b) Your face lift
c) John Wayne Bobbit
62. You know that pigs and bears are not necessarily rural wildlife.
63. Your roommate can be your roommate and not your "roommate."
64. You know that referring to someone as "a real lady" isn't necessarily a compliment.
65. Your favorite dinner accessory may also be your dinner companion.
66. If your cat is a female, you swear it's a lesbian.
67. If your cat is a male, you swear it's a lesbian.
68. You sing along with songs that make most females cringe, like "Stand by your man".
69. You've been to a bris, a barmitzvah, a christening, a first communion and too many weddings and you have a carefully considered evaluation of the food after each.
70. You'll never have to hear your mother complain about your wife.
71. A two-seater convertible seems perfectly practical to you.
72. You have a favorite Disney character and it's usually a nasty one.
73. You've left someone totally speechless.
74. You've shaved something other than your face.
75. All your friends do not have to "get along".
76. You have large collection of anniversary pictures. They may be with different guys, however.
77. Your love handles are actually used as such.
78. When someone turns his back on you, you actually consider it an opportunity.
79. You've got a large assortment of movie-star biographies.
80. You've got the most interesting coffee table books.
81. You know where to find a meat rack and it ain't in your kitchen drawer.
82. You have a sexual persuasion with its own flag.
83. At some moment in your life you've envisioned having back-up girls.
84. You know your enemies.
85. After a workout at the gym, you feel like a new man. And he's right there in the shower.
86 You're Barbra Streisand's biggest fan.
87. You know that Barbra Streisand's biggest fan is Barbra Streisand.
88 Not only have you added spice to your life - sometimes you've added side dishes.
89. You know that "small talk" can be about spirituality or politics, and "important issues" can be about hair.
90. You've actually lived out some of your fantasies.
91. Unlike most straight women, you have no problem being treated solely as a sex object.
92. You have no doubts about the accuracy of the Kinsey Report.
93. You know, by heart, every line in:
a) All about Eve
b) The Rocky Horror Picture Show
c) Your face
94. You are ALWAYS ready for your close-up.
95. You have 412 ways to tell someone to get lost. 136 are non-verbal.
96. You can lip-sync to at least one Supreme's song.
97. You have a carefully selected Yiddish vocabulary.
98. Even if you're in Kansas, you're not in Kansas anymore.
99. You know exactly how many martinis it takes.
100. When throwing a party, you know how to put out quite a spread. Sometimes after the party too.

http://www.funnyandjokes.com/100-reasons.html

You know your gay when you wear a jockstrap and don't do sports

You know you're gay when you know the difference between "your" and "you're" and don't need to put much thought into it. Lol. By the way, I'm totally joking and NOT giving the OP (much) shit. Just an amusing thought that came to mind.

You know you're gay when you don't know the right form of your. Kidding!