Firstly he knows because he has one, and was 12 at some point. Most men remember this initially embarrassing and emotionally trying problem of puberty as funny when they are fully adult. Lots of comedy is done about this issue which all men who went through puberty go through.
All boys in puberty get erections all the time for no specific reason. You may remember this.
The other thing to acknowledge here is that he is speaking dialogue written by someone else. So you've failed to separate him from the character he is portraying.
I know how hard it can be to do this but I'm saying it anyway, try not to take everything to heart often our abuse can distort present interactions w/o us even noticing.
Edited by kidneythis (11/11/09 08:02 AM)
As Mark Twain once quipped, history may not repeat itself, but it does rhyme.