a crusty bag is when a male puts his testicles in a large bowl of chocolate, waits for it to set and starts smacking it on the womans face so it starts to crack then anouther has too lick it off whilst its happening.
When a chick with a tracheostomy is blowing you and she inhales right when you come and the spooge comes out her throat hole and dribbles on your nuts. It's a crusty bagpipe with tartar sauce if there's boogers in it.
When a Frenchman falls asleep after having anal sex and awakens after a long period to find his penis to be encrusted in dried fecal matter thus resembling a crusty baguette.
Mimi phoned to ask me to pick up some fresh bread on my way home, to which I replied, what's wrong with the crusty baguette that you gave me last night.