Virtually every reader of this blog knows the mano a mano eggcorn (see here for details, using the mano-on-mano variant, with mention of mano y mano). Spanish "hand-to-hand" becomes "man-to-man" combat.
Tonight, Jon Stewart interviewed John "I am sooo history" McCain and produced an uncomfortable twist: Stewart offered to go mano-a-mano against McCain, surely in the eggcorny meaning. The latter, namely, suffered serious, lasting damage to his right arm in Vietnam when he was tortured as a prisoner of war. (He does have some use of it; for example, he did shake hands with Stewart tonight.) McCain clearly took the joke as intended by Stewart, putting his right arm out for an arm-wrestling match. Ouch.
Update, Wed. night Minor correction: Stewart actually plays off of the mano y mano variant.
Graphic by the famous Déro from here.