Term used to describe the event when a man is jacking/jerking/jagging off while viewing a dirty magazine with pornographic images such as playboy or penthouse, and the man splooges (ejaculates) all over the magazine creating a giant mess of man gravy on the magazine.
Johnny: Bro, i was totally looking at my penthouse magazine yesterday and there was this picture of this fine girl and dude i just let out my man gravy all over the magazine.
Beaver: Dude, you totally had a magjag Splooge.
Beaver: Dude, you totally had a magjag Splooge.
by Brycer August 20, 2010