Malk

Malk is a drink which is served with the lunches at Springfield Elementary School instead of milk.

History
Bart thought that the school served milk, but when he cracked his knuckles, they snapped painfully. Bart was shocked about brittleness of his bones, because he had always drunk plenty of milk. However, when he looked closer at the carton, he realized it was written "MALK" instead of "MILK".