Originally a sports term referring to players not giving 100%; more prominently used to describe trickery, swindling, or any form of cheeky shenanigans. Popularized by NBA Analyst Mark Jackson.
Vince Carter was fouled hard in the face, apparently having one contact-lense knocked out. While slowly making his way towards the foul line, he could be seen blinking his left eye and looking up towards the lights. After continuing to show signs that he could not see straight, VC took the ball, knocked down both foul shots, and jogged away laughing, pointing at Mark Jackson on his way back down the court. That's fake hustle.