The caterer.
or
Take your foot off his head.
or
One's a spineless, poisonous blob. The other is a form of sea life.
or
One is a blood-sucking parasite, the other is an insect.
or
An offer you can't understand
or
I don't know. There are some things even a blonde won't do.
or
A gigolo only screws one person at a time.
or
Stick his bill up his ass.
or
After you die, a leech stops sucking your blood.
or
To prevent clients from being billed twice for essentially the same service.
or