When a guy shoves a twinkie up a girl's asshole and then ejaculates on it. Afterwards, he gets another girl to eat the twinkie out of the other girl's asshole while on a schoolbus. The girl with the twinkie up her asshole then proceeds to finger her asshole and then eat the sperm and twinkie from her fingers.
Example:
Kid: Wanna get a dirty schoolbus?
Girl with tight asshole: Hell yeah! I love twinkies up my asshole!
Kid: Wanna get a dirty schoolbus?
Girl with tight asshole: Hell yeah! I love twinkies up my asshole!
by Average Kid December 08, 2016
When during anal intercourse you urinate inside of your partner. Yellow and brown like a dirty schoolbus.
by Mogged March 09, 2008