This is a combination of two sexual fetish acts.
It involves having a male defecate on you, followed by the recently defecated upon performing annalingus on the defacater while giving him a reach around hand job.
This is a combination of a Cleveland Steamer and a Rusty Trombone.
Thus: Cleveland Brassband.
Friend 1: My boyfriend shit on me and after that I licked his asshole while jacking him off from behind.
Friend 2: Oh, he gave you a Cleveland Brassband? I don't know which one of the two of you I'm more jealous of.