A person who is so stupid that they can be used as a literal dummy.
Person 1: Hey, can you buy me something?
Person 2: Yeah! Do you have money?
Person 1: Yes, inside your wallet
Person 2: Great! I already have it for you!
Person 1: Thanks! Stupid Dummy!
A stupid dummy is someone who lacks knowledge or who has no common sense or any experience in real life situations or someone who is portrayed as a gook
Buddhaman: ”Wazzup wit jitt he over there gookin”
ZellyB: ”Jitt ain’t never see this type of shit he a stupid dummy”