Anthony told Chirs a joke, and Chris then repeated it to everyone else, and took credit for the joke, thus bodybagging. Chris boddybagged the joke and is an asshole.
A boddybagger is a term used when a girl has a nice face but an extremly fat or ugly body and you must cover her body with a bag before you receive head from her.
Don: "hey man you know gena?"
Lorne: "ya what about her?"
Don: "well i bodybagged her last night and dam was it good"
Lorne: "sweet i should get me a bodybagger one of these days".