Nose adjustment
One of the semi-magic tricks Peter used to occasionally do:
He’d say that his nose was out of alignment or something, and needed an adjustment, like a chiropractic adjustment.
He would put his hands together palm to palm, as if praying, but with his nose between the index fingers.
Then he would bend his hands to one side a little several times, as if twisting his nose slightly around an invisible axis coming straight out of his face; he’d indicate that he was taking out the slack. Then, one last sudden sharp bend/twist, accompanied by a loud cracking sound.
The trick was that he had one thumb (hidden by the other fingers) in his mouth in such a way that the thumbnail was under an upper front tooth; at the moment of bending his hands, he would snap the thumbnail out from under the tooth, making a noise.
When done well—and Peter did it well—this trick can be remarkably effective, and Peter took great delight in performing it.