This was a weird one. Teen boy and girl have sex. Afterwards an alien causes his penis to grown and and her stomach to grow. She then (unknowingly to her) spits the alien in the toilet. the alien grows in the sewers. I saw it on IFC about seven years ago.
Class of Nuke ’em High
That’s it. Solved.
That was painless. Haha. Thanks for the quick confirm, vl00122!
Solved!