Or, y'know, a ball.
Screw the ball, prom is where it's at.
Fiona can turn up to Thetis's house, be accosted by some parental figurehead (probably Idris) about doing the dirty with her little gem. They get to prom, Fiona shows that as well as being socially awkward and more buff than the football team she can also pop and lock with the best of the kids.
The evening ends, Thetis kisses Fiona awkwardly showing romance is alive in the world.
Then Fiona drives Thetis to a cheap motel, boinks her brains out implanting her with her fiery seed only to never be heard from again.
Ladies and gentleman I give you my first novel!!!!