When you're dancing or having sex
with a really fat (and ugly) girl, and you're being really Romantic. Then, after a while, you go behind her, hug her round her neck and whisper sweetly into her ear saying something like...
"You're reeaaallly fat"
...And you have to see how long you can hold on
"Dude, I was having a hardcore session of fat girl rodeo at the club last night, you should'a seen her man, thank god she counldn't reach me."
My fat girl rodeo record with her is like a whole minute or something, you would have thought she'd have learnt the game by now...