A simile generally referring to sex.
"
Screwed like a
virgin on
prom night"
There are many other take-offs of this. For instance
"
off like a dress on prom night".
The idea is that
virgins don't make it through
prom night without losing their
virginity. This isn't particularly true...while
prom night is an excuse for more sex for some
couples, it's generally only ones who were already having
sex anyway.