I find that I cum a lot faster if my gf has been playing rough with my balls (squezing and tugging). I've been able to cum from her tugging on my balls up and down, but it does mave my cock also, so maybe that doesn't count. As for self-abuse, I've been able to make myself cum through ball punching, much like "vulneraballs" said by rhythmic repeated punches starting soft and getting harder as I get closer to climax.

