I know that at least in Japan, cheeky translators use funny or obscene English on purpose for free publicity on the internet, like the clothing brand Fuctard. Not sure it applies in this case, though.
Calqued "hot dog" (热狗) with transliterated "doughnut" (多拿滋), which is like "lots of - get - (to) grow/nourish" if you attempt to parse it as a real Chinese word (character meanings often influence the specific transliteration). The "zī" character (滋) is also used phonetically in the transliteration of AIDS (艾滋病), which is the connection, but I still can't really see how this happened.