It happened one day as he was with me as I attempted the task of folding clean bed sheets to be put away. I have trouble rolling sleeping bags, so you can imagine how much fun I have with huge sheets. I can't remember the conversation verbatim, but this is close to how it went:
Karl: Why are you folding them?
D: Isn't that what you do?
K: You can just stuff all the sheets into one of the pillowcases.
D: ...*ponders for a moment* But wouldn't that make them all wrinkled?
K: They're bed sheets. They get wrinkled anyway.
Touche. Score one for the Kar-man.