Cardi B and Offset Sued by Autograph Hound Who was Beat Up After Met Gala

Cardi B and Offset have just been sued by the autograph hound who got beat up by who he claims were Cardi and Offset's hired muscle ... TMZ has learned.

Giovanni Arnold claims he was at The Mark Hotel just after 2 AM on May 8 -- outside a Met Gala after-party -- when Cardi walked out and shouted at him, "F*** outta here n****, I will slap the s*** out of you."  He says he "expressed disappointment with being ignored."

Arnold says shortly after Offset, who was trailing behind his fiancee, said, "Shut up, bro, before a n**** beat you out here."

According to the lawsuit, filed by Daniel Szalkiewicz, Arnold says he tried de-escalating the situation, but within seconds 3 bodyguards attacked him. He says he didn't fight back. All he did was lie on the ground and try to protect his body.

He went to a hospital and says he suffered injuries to his face, neck, back and body.