Crab

Why would you never donate to crabs?

Because they're shellfish!

Site

What did the substrate say to the active site?

"C'mon baby, we fit together, open my door lock to f**kin' key."

Baby

Some babies may be delivered via stork, but some bigger babies are gonna need a crane.

Napkin

My friend tried to sleep on napkins.

I guess that's why they're called NAP-kins.