I hear stories of SBD gunners bringing cans with them to throw out to fool Japanese pilots into thinking they were reloading.  It was a counter tactic to the Japanese pilots tactic of waiting for the reload to make an attack pass.  
That would have been an even better tactic with a 'loaded can'!!!  Maybe even obscuring the enemies vision or fouling their engine.  Thats a big maybe, but it certainly would be foul!