After a particularly lousy landing made from the right seat of a commercial airliner, that FO heard the Captain announce "Ladies and gentlemen, XXX Airlines wishes to apologize for that rough landing provided today by our First Officer."
Some months later the same crew was together and, sure enough, the Captain made an even worse one. The First Officer immediately jumped on the intercom, announcing "Ladies and Gentlemen, XXX Airlines wishes to apologize for that rough landing provided today by our Captain."
The Captain turned angrily to his FO. "What did you say that for?"
"Remember a couple of months back when you did that to me?" the First Officer replied. "Now we're even!"
"But I never keyed the mike!" protested the Captain.