Funniest two liner ever

Courtesy Calvin & Hobbes:

Calvin is flying in his fighter jet plane, an awesome green coloured F-4 phantom with yellow patches on it with sharp pointy black nose and with screaming fire coming out of its ass. Suddenly a voice cackles in Calvin's radio,

radio: "Enemy fighters at 2 o'clock"
Calvin: "Roger. What should I do until then?"

omg this one's even better:

Calvin: Look it says you need to be eighteen to buy cigarettes.
Calvin: (frantically)EIGHTEEN?!? By then I'll know better!