Means stop sucking dick. In spongebob, theres an episode where the krusty krab sells Kelp drinks and it shows spongebob slurping on the straw, so it means stop slurping on dick.
Matthew: "Oh my god Nathan, you have the best handles and the best shot in basketball and youre really good."
Nathan: "Thanks?"
Nick: "Put down the kelp matthew, jheeez"
Nathan: "Thanks?"
Nick: "Put down the kelp matthew, jheeez"
by fumastyle November 5, 2017