Calvin and Hobbes by Bill Watterson for September 27, 1993
Calvin: Psst, Susie! What's the answer to question two? Susie: "Eli Whitney and the cotton gin." Calvin: But this is a math problem. Susie: It's a trick question. Calvin: How come you wrote something different? Susie: I'm going to get this question wrong, so ti won't look like you copied. Calvin: Wow, thanks! Susie: Oh, I owe it to you.