Boquete is the most common Brazilian Portuguese word for a blowjob.
People realized that the English words "ball cat" sound like it. This joke became so common that eventually they were translated back into Portuguese, and bolagato (bola - ball, gato - cat) became a common code word for a blowjob.
This whole process is so specific that I don't think there's a name for it, but are there similar examples in other languages?
native word -> literal translation of foreign words that sound like it