Golden anniversary

On an airplane, I overheard a stewardess talking to an elderly couple in
front of me. Learning that it was the couple's 50th wedding anniversary, the

flight attendant congratulated them and asked how they had done it.

"It all felt like five minutes..." the gentleman said slowly.

The stewardess had just begun to remark on what a sweet statement that was
when he finished his sentence with a word that earned him a sharp smack on
the head:

"...underwater."