this means smoking marijuana with your gang affiliated members (mandem) on the corner on the endz. this is often accompanied by singing this song:
we’re going on a trip to smoke a big fat spliff. Running through the endz with the Mandem, climb on board get ready to explore the world of green, me and my weed.
mandem 1 - yo mandem. shall we go smoke a spliffy wiffy on the endz
mandem 2 - yeah styll but only if we can sing the song first my bredrin