Most commonly described as a girl with a great body but a mangy unlovable head..
Also used in relation with "seafood lappy": the act of a prawn stripper giving you a lapdance.
"seafood smorgasboard": where a room is filled with prawns, so many prawns it can make a man gay...or a lesbian want to have a crack at the wang..
"don't hook that chick, she's a prawn"
"i got a seafood lappy last night, i told her she wasnt worth $50 so i gave her $10 and told her to turn around"
"lets bail, this place is a seafood smorgasboard"
"you mutant prawn, i'll slap your arse up and your face off...then we'll talk!"