This can be seen nightly on any game in the NBA.
After Team A scores a basket, a player from Team B goes to inbound the ball. I have played basketball up to a high school level. From my understanding, after a basket, the other team must stand in OOB behind the baseline (whereupon this player can even run the length of the baseline until he passes it in, or 5 seconds, or a time out).
But, what you will see on a nightly basis - in the NBA. College I don't remember seeing it - is that the inbounding player will hop as if to touch out of bounds, but pass inbounds before actually touching down.
I'm pretty sure this is illegal. Why is it allowed?