To "dip" out, in a sense
To lean or slump your head over due to excessive intake of marijuana or other narcotics
To react very slowly or stupidly
"dude look at deshawn, hes slagging hard as fuck right now"
"Just facialed 2 blunts of white widow, Im all slagged out right now"
"Were always on that shit, hashtag SlagSquad"