Funny! Just so you know, you're not alone, I just wrote about this in the Maxi thread. She had sent me her "play dead" technique. So I taught it to Coby less than a week after he learned "shake". (He already knows "sit", "down", and "stay".)
So now, when I go for the treats but before I can get any into my hand, his butt slams onto the floor in a sit, then his paws start flapping all over the place trying to shake, then he flops down in a lay position, and then rolls to his side playing dead - all within about 5 seconds!! Coby has explained to me that waiting for a command is very inefficient. He knows what they all are, so he figures he'll just whip 'em all out to make sure he covers the one I'm looking for!!
I decided that our next trick/command will be "wait till I tell ya".
Hang in there!