Well I guess the "achievement of
erection"
in the male
gender, but it can also represent a mental state,
maybe in girls too, I dunno....
1) "Well, first ya
git 'er down on 'er hands and KNEES.... Then ya reach around and grab a handful o'
BOOB... Then see if ya don't get a hardon !!!
2) "Yeah, I'm just BitTorrenting some more John Holmes..."
"Dude, I have a total hardon for what you're doing !!!!"
3) "
Wow, that was a HARD hardon !!!!"