look up any word, like half chub:
 
1.
The act of two or more sisters engaging in sexual intercourse with one or more men, usually in a threesome or an orgy.
Ah, if only Brigid had a twin, we would totally get a sister act going in my bedroom.
by Robert Crumballs May 12, 2005
 
2.
a feeling of total annoyance of the ingnorant ghetto wannabes around you
I feel totally sister act, those bageenies won't shut up.
by Anonymous March 17, 2003