This particular way of holding a deck of cards has become known among magicians and card sharps — you know, cheaters — as the Mechanic’s Grip. It’s a good way of keeping control of the deck while still being able to deal seconds, or off the bottom, both useful techniques if you’ve switched in a cooler. So skilled card cheats will avoid using the Mechanic’s Grip because it might give them away. But it’s also a very comfortable way to hold a deck of cards, and it’s one that many novice players adopt by coincidence.¹

This means that, if you’re playing poker with someone who holds the cards in the Mechanic’s Grip, you immediately know one of the following is true:

• They’re cheating.
• They’re not cheating.

In the left hand, however — and substituting an iPhone 4 for the deck of cards — the Mechanic’s Grip is also known as the iPhone Death Grip. It’s a good way of keeping control of the phone while still appearing to lose about 30% of your 3G signal. So skilled iPhone users will avoid using the Death Grip because it might fuck up their reception. But it’s also a very comfortable way to hold an iPhone 4, and it’s one that many novice users adopt by coincidence.

This means that, if you’re playing poker with someone who always complains about the signal strength of their iPhone 4, then they may or may not be a big fat cheater.

Hope this helps.