1) A time during summer when certain seafood eateries start selling crabs to buyers in mass quantities; crabs are usually steamed and dipped in butter.
2) Whenever a MILF/whore/hooker is infested with crabs.
1) Phil: Let's go to crab fest at the restaurant down the street!
Susie: I love crabs!
2) Bill: Dude, your mom is a total crab fest. I'd tap that.
Tanner: ...That's nasty...