Do you get rough with bending, squeezing, twisting or pounding? Do you ever crush it with something (like book)?

Yes, mostly like to smash it flat.

Numerous times I've grinded my cock against a hard surface, a wooden floor or a steel pole for example. I can't really explain the sensation but it feels great.

i do too, squeeze with big clamps

I do a rapid squeeze release over and over. It's become such an automatic thing I didn't even think of it till I was doing it in bed this morning. After a little while of doing it my cock becomes engorged and erect ready for stroking

I quite like slapping my dick and balls and sometime use a home made flogger

yeah I have always enjoyed getting rough with myself. I first started by sticking my cock between the toilet seat and the toilet and putting all of my weight on it. Since then I liked to grind on hard rough surfaces like trees. I ask my partners to bite my cock and squeeze my balls. I tell my wife to grab me by the balls and pull; she'll be on her knees as I am on my back and just grab them and lean back holding herself up by my balls. I love it. Too bad I haven't got her to walk on my cock yet.