Yes, that's what I actually meant to ask.
A guy friend of mine told me about this one time he faked cumming when he got a bj. Yeah, it's pretty obvious that his girlfriend/bj giver was an idiot if she fell for that.
And you are right, younger guys do tend to have a shorter trigger. They see an attractive girl and they have a boner. On the other hand, it seems that older women have that type of trigger as well (This is based on people I know, not trying to make a generalization). I can't just see an incredibly hot guy and get wet on the spot, but then again there are probably at least a few that could have that effect on me lol.
Have you ever heard of thinking yourself to orgasm?