It is an acronym for "Yao Only Fan." It is a racist phrase intended to put down Chinese fans of Yao Ming, who do not otherwise have an allegiance to the Houston Rockets, the team Yao Ming plays for. Longtime Rockets fans are offended that there are people whose primary allegiance is to Yao Ming and not the Houston Rockets.
I can't believe that little Chinese guy is mad Yao did not get enough shot attempts even though the Rockets won the game! He must be a YOF, he only cares about Yao Ming getting good stats. Plus, his grammar is bad, he is probably from China, a stupid communist country.
Someone who "claims" to be a Houston Rockets fan, but in reality they are only a Yao Ming fan. They do not care about the Houston Rockets or Tracy Mcgrady, only Yao Ming. Hence the term YOF (Yao Only Fan). If Yao is injured or sits out a game, they want the Rockets to lose, so that they can say, "I told you so, the Rockets are nothing without YAO". YOF's are never not asian.
Huang is an annoying YOF. He knows absolutely nothing about basketball, he isn't athletic, and he's never kept up with any professional sports team in his entire life, but ever since the Rockets drafted Yao Ming, he's become the biggest die hard Rockets fan I have ever seen. Wtf?