Cupid Shuffle Guy Sued -- Down, Down, Pay Your Bills ... Pay Your Bills

Cupid is being slapped with a lawsuit -- not for causing more bad wedding reception dancing than the Macarena -- but for not paying his manager more than $100k.

Brick Wall Management filed the Federal suit in NY against Cupid -- real name Bryson Bernard -- claiming he signed a deal for the company to manage him ... back in 2007 ... the same year "Cupid Shuffle" was released.

TMZ obtained a copy of the suit, and in the docs BWM alleges Cupid agreed to pay commissions to the company for a period of 15 years.

BWM claims it can't calculate exactly how much Cupid owes in commissions because he refuses to reveal any details about his income -- so they're guestimating at least $100,000.

Calls to Cupid's reps have not been returned -- but we suspect the real issue here might be he hasn't had a hit since the 'Shuffle.' So, really ... what's to manage?

Ok, go ahead ... y'know you want to do the damn dance.