Ah, I see how you reached the deepest part of the Urban Dictionary just to hear me tell a story. I shall tell a story then...
Stone is basically a kind of rock. Stone is also a name for someone but it’s an odd name.
Basically if you’re called Stone then they mean you are dumb and your brain is basically a stone.
“Hey, look at that suspicious stone!” Said a young child “What are you talking about? I’m Stone!” Said Stone
“Oh... then you’re dumb hah!” Replied the young child.