The old "center snaps the ball, QB touches it while lineman then takes it from the center while he's holding it to his butt" play.
This play has been illegal for as long as I know. I do have coaches who explain this 'trick play' to us pre-game, so I think some referees might wrongly allow it.
A snap MUST leave the snapper's hands and either (a) hit the ground or (b) a player behind the line of scrimmage. If it doesn't it's a false start.
A QB can receive the ball (after it has left the snapper's hands completely), then once the snapper turns around 180 degrees to his own goal-line, he can then accept the ball legally.