Two days ago, we unintentionally created a joke that you need 3 languages to understand. Here is what happened:
My now 7-year-old daughter was practising looking up words in her new German elementary school dictionary. As she was looking for Fledermaus, she came across a word she didn’t know, and asked me: “Flattratte?”
It’s a funny word, flatt meaning flat and ratte meaning rat, but obviously it doesn’t exist. I looked over her shoulder into the dictionary and saw this:

I told her it was a word from English that is used in German but pronounced the English way. After I finished laughing, that is. Then I asked her to continue looking for her Fledermaus while I wrote the Flattratte down before I forgot about it. On the way to my desk I thought I’d tell her dad, too. Since he doesn’t speak German well enough to get the joke, I told him in French our daughter had read a word as “flattratte”, with flatt meaning plat and ratte meaning rat – a flat rat.
Him: “A pigeon?”
Cue my second fit of laughter.
(In French, pigeons are sometimes jokingly referred to as flying rats (for obvious reasons), and here in Paris often encountered as road kill – flattened.)

See? Impossible to tell this joke without long explanations if you don’t understand all three languages.