Bam Margera is up to his old tricks ... lending his "Jackass" experience to a new group of wild daredevils and helping them film a brutal knockout video.
The former "Jackass" star shot a couple stunts over the weekend in L.A. with the MadHouse Boys... throwing on a boxing glove and unleashing some haymakers to the head.
In the footage, obtained by TMZ, you see Bam sneaking up on one of the MadHouse Boys from behind and punching him in the side of the head, and it looks like it hurts .