Jake Paul Sued By Man Claiming He Got Beat Up at House Party

Jake Paul's after-party following his knockout of Nate Robinson had a beat-down of it's own ... at least according to a new lawsuit.

The YouTube star and undefeated boxer is being sued by a man who claims he got the crap beaten out of him at Jake's post-fight bash. According to new legal docs, obtained by TMZ, Gabriel Dos Santos claims Jake's crew beat the snot out of him while kicking people out of the party.

In the suit, filed by attorney Simon P. Etehad, Dos Santos claims Jake's crew repeatedly kicked and punched him in the face, body, arms and legs ... and he claims the violent attack left him bruised and battered.

According to the docs, Dos Santos claims he suffered a fractured cheek, dislocated shoulder, cuts to his face and bruises to his forehead and eyes.

Jake's not being accused of throwing any punches, but Dos Santos claims Jake's still on the hook for negligently hiring and supervising of the guys who allegedly beat him up.