1. A man or woman's crotch; colloquially used to refer to a person's genital area.
2. A man or woman's lice- or "crab"-infested junk.
"I invaded Britney's crabitat last night, and now I'm itching like a mofo."
Crabitat can describe any habitat suitable for any species of crab (decapod crustaceans).
Low tide exposes lots of good crabitat, yo.