Calvin and Hobbes by Bill Watterson for October 03, 1988
Calvin: For show and tell, I brought a space alien I captured in my back yard. Yes, for the last two days I've been kiiping it in this special zarnium-coated bag, and feeding it pure amonia! And now, the moment you've all been waiting for! Aargh! Hobbes: How'd it work? Calvin: My teacher says Mom and Dad both have to sign my report cards this year.