Appropriation of sports team logos is a pretty common t-shirt trope that, with a few notable exceptions, usually goes ignored by the teams themselves. If you do wish to draw the ire of a sports franchise with your brand-jacking, your best bet is to make it offensive. From NBC New York:
The shirt, sold at the store on 38th Street and 10th Avenue, starts off with the Knicks spelling, but replaces the end of the word with "g-g-a." It retailed for $45, $10 more than an actual Knicks t-shirt.
"Everybody's buying," said store manager Eddie Nunez.
"Everybody" buying the shirts may be the very reason the Knicks took notice and stepped in:
The real New York Knicks were not happy about the offensive lookalike. The team said in a statement, "We absolutely do not condone this t-shirt, which violates our trademark rights and now that it has been brought to our attention, the Knicks are working with the NBA to have the store cease and desist from selling them."
After some deliberation, the store manager has decided to remove the shirts from his shelves. Probably better off that way.