In programming languages today, someone had to answer this question:

Prove the contention on page 40 that when a CLU iterator terminates, indicating to its parent for loop that there are no more values, the iterator’s activation record is actually at the top of the stack.
— Advanced Programming Language Design by Raphael Finkel, p. 61

The guy’s answer wasn’t the funny part, but he did summarize with something like “those were the only cases I could think of, and the claim is true for those”, which led our professor to call his proof a “proof by failure of imagination.” He then told us about another proof by failure of imagination: intelligent design. He explained it thus: “The universe is too complicated to have just sprung up and I can’t think of any other explanation, therefore someone must have created it.” Ha!