One is a blood-sucking parasite, the other is an insect.
or
But I don't want to be naked in an exam I haven't revised for.
or
"The erection is rigged!"
or
Because people are dying to get in!
or
With sheets of ice and blankets of snow.
or
One's a spineless, poisonous blob. The other is a form of sea life.
or
Two, one to screw it in, and another to repent.
or
They can hit the high C's!
or
Snow White Supremacist.
or
Take the pizza delivery sign off the roof
or