In French, we have a kind of humour called contrepèterie (maybe it isn't unique to French, but I've never come across it in any of the languages I've studied).
It's a kind of play on words that consists in switching around two or more phonemes in an otherwise innocuous sentence to get a different, usually salacious sentence. Some examples:
1) La Chine se dresse à la vue des Nippons, translating to "China rises at the sight of the Japanese", becomes, if you switch the sounds in bold: La pine se dresse à la vue des nichons, which means "The dick rises at the sight of boobs";
2) Quel beau métier, professeur !, "What a wonderful job, being a teacher!", becomes: Quel beau fessier prometteur !, "What beautiful, promising buttocks!";
3) J'arrive à pied par la Chine, "I arrive by foot from China" becomes: J'arrive à chier par la pine, "I can shit through my dick";
4) Je vous laisse le choix dans la date, "The choice of date is up to you" becomes: Je vous laisse le doigt dans la chatte, "I leave my finger in your pussy".
Does your language have a unique kind of humour?