[The Megan 2207]

A freshman didn't make a very obvious connection during a conversation...
Me: Go... hit your head on a wall or something.
*freshman hits head on table*
Me: No! A WALL!
Freshman: I don't know where a wall is!
...We were inside.

Later, building off of that joke...
Me (to a different freshman): Go hit your head on a wall.
*different freshman walks toward whiteboard*
Different freshman: Oh wait... that's not a wall.
...That's when the programming team decided If freshman=true then wall-finding skillz=0.