Can you fumble backwards out of bounds on purpose?

Mere conjecture, but......

The ball would probably be placed at the point of forward progress and the clock kept running. That in itself would be enough penalty as the clock continues to run. <B>IF</B> a further penalty was warranted, it would most likely be a ten second rundown from the pont of the ball going out of bounds, after which the ball would be whistled into play, leaving the offense a slight chance of getting the play off if there were more time left.

No hard rule, just MHO.