Just saw this comment on Stack Overflow, and thought it too good not to repost...
A programmer's wife sends him to the supermarket. She tells him, "Buy a loaf of bread, and if you see some eggs, grab a dozen."
The programmer later returns with a dozen loaves of bread under his arm
Note: A subsequent comment pointed out that if he were a real programmer, he would have returned with 13 loaves!
A cracker!