I'm going to supply the context for this as well as my favorite part of the whole ordeal.

Context:

Teacher: *draws a globe with latitude and longitude while wearing a striped sweater*

Girl: Your shirt matches the board!

Teacher: *pins himself against the board* I'm camouflaged!

Boy: You're a globe!

Class: *loses it*

Sometime later:

Teacher: *to boy* Watch yourself. You called me fat.

Boy 2: You call him fat?

Everyone who heard him: *loses it*