Aw man... but all jokes aside, it's a monster/mob from the game Minecraft. It's green and shaped like a penis, but that was NOT intentional. 1 of the creators of Minecraft, Jeb, stated that it was a faild pig design when Notch flipped around the Y-axis and X-axis by accident. The creeper explodes when a player is near it, and usually spawns near builds that take a long time to make (so annoying 🙄).
Player: I sure do love building this hou- aw man.
Creeper: BOOM!!!!
Player: I quit Minecraft...