this is the actual show flyer, and a screenshot of Little Shalimar's Facebook...
Union PoolUnion Pool
Union Pool

My first guess, based on multiple clues above, is The Phenomenal Handclap Band, though then I don't get what the secret is all about. Who do you think is playing with Little Shalimar and Tit n Twat at Union Pool tonight (7/12)?

UPDATE: Antibalas, who also plays Fort Greene Park today, makes much more sense (thanks Andrew)