Vader feels the power of the Force. The Emperor messes with Vader by using the force to squeeze his cheeks as an adult would a little child....
Anyways, here's the elusive rubber Halloween mask. I think it's a Rubie's. Interestingly, the nose is the characteristic shape of the MR ROTS helmet.
So anyone want to buy one of these, fill it with foam and idealize its shape? Add some bondo here or there, and pass it off as a "Mystery Helmet"?
A Vader fan's worse nightmare? His wife going, "Honey, I bought you a Darth Vader helmet for your birthday at a great price! SURPRISE!" And it turns out to be THIS!