A true story from the Australian Aviation magazine
After a particularly lousy landing by the co-pilot of an Australian commercial airline, that co-pilot heard the Captain announce "Ladies and Gentlemen, XXX airlines wishes to apologise for that rough landing provided today by our first officer".
Some months later the same crew were together and, you guessed it, the Captain did an even worse one. The First Officer immediately jumped on the intercom announcing "Ladies and Gentlemen, XXX airlines wishes to apologise for that rough landing provided today by our Captain".
The Captain immediately responded angrily, "What did you say that for?".
The First Officer replied "Remember a couple of months back? I owed it to you!".
"But I never keyed the mike!", responded the Captain.