Is an expression meaning: To do something; to get something done or taken care of.
Katie: Dude when are we gonna go and smoke a bowl?!
Eli: Dude fuck I'm waiting for the delivery service to come bring the sack
Katie: But dude it's like 4:10 and 4:20 is in 10 minutes?!
Katie: I thought i told you to get on that shit!
Eli: I know! I Know!