Sounds like the story I read on a business travel forum about the Texan couple who the writer sat next to, on a Lufthansa flight from the USA to Frankfurt. The steward comes round with the lunch trolley and asks the gentleman where he and his wife are going. The Texan replies: " Well last year we went to Munich and we enjoyed ourselves so much that we thought we'd go again except to a different town, so this year we're going to Munchen".
"But Sir," replies the LH steward, "Don't you know that Munich and Munchen is the same town?"
"Oh really? Looks like we goofed there. Oh well, we might as well go again!"
"Well never mind," says the steward. "How about some of this caviar?"
"Cav-viar? Cay-viar? What's that?"
"Oh you know Sir, just fish eggs!"
"Sure.... give me two!"
At which point, reportedly, the German steward rushes off to hide behind the curtain of the galley from which the sounds of barely-suppressed hysterical laughter can be heard for the next few minutes.