2. To sit down suddenly.
3. To hit something or someone hard with an object.
2. Plunk yourself down right here next to me.
3. The teacher plunked the boy on the head with his backhand before he could lift up the girl's skirt.
Named for the fact that when you drop one, you make a plunk sound.
Mom: "PLUNK, your dead bitch!" (as she runs away.)