your 'raas' is your bum, a 'claat' is a cloth. Toilet paper!
This is the actual meaning, but it is often used as an adjective when expressing disatisfication.
one would be comparing something to toilet paper, waste...
Patois: Shut yuh raasclaat mouth
English: Shut your filthy toilet paper mouth
Generic curse word often used to curse or when one is exicted. The word itself does not have a definite meaning. It is often prefixed with other curse words such as bumbo or p**sy e.g. bumbo-rassclaat
Patois: Weh di rassclaat a gwaan yah suh?
English: What the f**k is going on here?