We often masturbate but go to seperate rooms, I will say while we are watching tv anything "Im having a wank, you can stay if you wanna watch" because apart of me actually does want him to lol but he always eventually goes to another room, he even says all the time how small his cock is so my argument for next time is "you always complain about how small it is lets just measure snd compare for a laugh", I really wanna see if I get him to show me his cock

Next time tell him:
"Hey,we both jerk-off and I see nothing wrong with jerking off in the same room to the same things."

I wouldn't say let's compare cock size because if he is really small, he might get embarrassed and your friendship could be in jeopardy.

I think your friend really does want to masturbate with you and I'm glad you're open to doing it with him. You have to be patient with him though sounds like he's terribly shy about exposing his cock to you. IMO if you continue to encourage him gently he will let you see it. If you can get him to open his fly you're home free.

A tricky one as thinking it and plucking up the courage to actually do it are poles apart (no pun intended about poles). Leave the door open to it, even playfully encourage it. Never quite worth forcing the issue though as things can 'go weird' in a big way and its not something that can be easily undone. I've seen that kind of thing happen to both males and females I know and it can be messy and also quite embarrassing if you misjudge the situation too much.

Yeah it's tricky for sure but it sounds like he really is interested just shy about it. Playful encouragement and assurance that it's OK making him feel comfortable and receptive to it. Anyone has to feel that this is "OK" to do.
That's where friendship and supportiveness comes in. Eventually he will feel comfortable getting his penis out I think.

I've been nude and Jack in with guys since before I could come.
In college and a few times that i've had roommates, I started lingering, still nude, after taking a shower...shaving, etc. to sort of show him I didn't mind if he saw my little 4"er.
After a few weeks I'd start watching porn with him, with just a robe on, and we both knew what we were doing when we went to our rooms.
After a few weeks. I said, "Fuck It," pulled my robe open and started jacking off. Shot my load up on my stomach and chest...a few minutes later, he pulled his dick out and stroked himself til he came.
This has worked with 5or 6 guys that I've roomed with.

Yes a comfort level has to exist. friends should start with that just being friends. being comfortable around each other. Lots of guys want to just yank it out and start beating it. But to someone new to it that's a shocker and a turn off. This guy is on the right track because he's going to other room to jack and I think he really wants to jack with him. It will take time but one day he'll get his penis out and join.
Remember if you've never been swimming before it won't pay to just jump in. Learning is needed and it's the same with giving and receiving male comforts.

I have a friend who is very similar. I've seen him naked several times and even watched him get blown and fuck his girlfriend. He's got a nice big dick. Nothing to be ashamed of.

We have watched porn together several time and both been hard. I tell him I need to cum and he encourages me to jerk off. He watches me, but he won't join in. I have a small cock, so it's not a matter of him being insecure about his size...his is much bigger.

He says is, "gay" to jerk off together and simply won't do it. He has gone in another room and jerked off while I was jerking and we talked through the door. I've heard him shoot his load and everything...but he just won't get naked and jack off with me.

He's dealing with long held social taboos placed on the act by uninformed society. He watches he probably wants too. I think it's quite normal so maybe you should focus on friendship , discussion and encouragement he may come around in time when he gets comfortable with it. Another possibility is he has fears that it might lead to other things and it scares him. Explain what you're interested in and where you are with it. The key is making him comfortable with it.

It does make me laugh when being openly aroused in closed company and encouraging you to whack off in front of him isn't 'gay' but joining in would somehow be.

Thinking back to my own formative years and similar hang-ups then I think I realised being in close proximity to a couple of other guys in a similarly undressed and very aroused state probably meant any line in terms of "this could be awkward if people found out" had long, long since been crossed. So from that point you just go with it and be damned!

it does not make a lot of sense that your friend will watch you jerk off, but then says it is gay to jerk off together? although I refer to myself as str8, I don't like how labels get placed on things, labels can keep people from trying and doing things that they might find to be just plain simple fun, personally I might have a hard time feeling comfortable jerking off with a friend that I have known for years, or a life time. but if it was something that came up early on in the "becoming friends" phase, I think I would really enjoy it

That's the way I feel about labels. The heck with labels sharing with a male friend is fun and exciting. This guy definitely wants to which is normal but I think he hasn't worked out internal issues with it. I think if a long time friend wanted to jack off I might wonder why it had taken so long to bring it up but I most likely would do it. People don't realize how much labels do to harm others. That's why I try to encourage a man to go with what he feels is right for him.

My thought on why he won't jack off with me is that he's actually gay and is either not attracted to me or he doesn't want to risk harming our friendship.

He lives alone, he's never been married, doesn't have a girlfriend, and is constantly telling me about women he fucks as if to say "I'm a heterosexual sex god". He's only had three girlfriends since I've known him (over 15 years) and one of them told me she wanted to get married and he broke up with her. She also said he refused sex with her regularly claiming he was "too tired". One of his GFs lived with him for a year but they slept in separate rooms. He claimed he couldn't sleep with her in the bed.

I think he's really gay and simply in denial.

Well I guess he could be but remember relationship problems doesn't mean you're gay either. I've know the blustering blowhard types and they're usually very insecure looking for approval. My take is that jacking off with a man improves friendships and brings men closer because you're sharing intimate masculinity. Guys love the masculine form. You would think he'd want that. Keep working on it, I hope you can get him to undress and enjoy it.