- The Dead Fish. This is the guy (or girl, for those girls who use male-type handshakes - badly) who just puts a completely limp hand in yours and maybe moves it up and down a bit. This is totally Not Cool. If you're doing it, you probably don't understand the handshake to begin with, so it's probably not really your fault. But you're really disgusting the people whose hand you shake who know better. Trust me on this. It's bad.
- The Firm Shake. In this handshake, you take the other person's hand in a firm but not crushing grip - say, the kind of grip you'd use on a screwdriver when attacking a fairly tight screw. If the other person's grip is a little weaker, you'll ease off on your own a bit to match; if the other person's grip is a little stronger, you'll tighten yours a bit to match. This is the basic friendly handshake. It says, "I am worthy of your respect, and I see that you are worthy of my respect."
- The Strength Contest. This one starts out just like the Firm Shake, except that each party then gradually ratchets the grip strength up either until it's clear who's the stronger, or until neither can grip any stronger without obvious red-faced exertion. Onlookers will generally have no idea what's going on, but the people actually shaking hands get a firm measure of each other's strength, without actually trying to hurt one another. As soon as the outcome is clear, or both parties have reached the maximum grip they can manage without totally white-knuckling, the ritual is over. This is definitely A Guy Thing, but it's still a friendly shake.
- The Bonecrusher. Much like the Dead Fish, people who use this one may or may not realize what asses they're making of themselves. In the Bonecrusher, every last bit of grip strength is applied right from the start, in an effort to get the better of the other party to the handshake. Even the Strength Contest doesn't go any further than it needs to to establish the relative strength of both parties - and goes slowly from a Firm Shake starting point to make sure both parties are willing to go there - but the Bonecrusher is an all-out, floor-it-right-off-the-line attempt to squash the holy fuck out of the other guy's hand.
It's amazing how much communication can go on between men in a handshake that the rest of the room never has a clue about. Like - just to f'rinstance a f'rinstance - you could meet some construction-worker dude, go for a Firm Shake / Strength Contest, but he goes for the Bonecrusher. So you grip back hard enough to keep from getting your knuckles squeezed, but, cold sober and just having met the guy, you leave it at that, and he thinks he's got the upper hand. Then several hours and several drinks go by, and you watch the construction-worker dude move from hitting shamelessly (and tactlessly) on your friend, to hitting shamelessly (and tactlessly) on your friend's roomate - because the roommate has a half-inch more chest exposed. And so when the dude leaves, and shakes your hand again, you don't let him get the jump on you - this time, you jump straight into the Bonecrusher with him - and come out on top - and you watch his eyes widen just a little bit as he realizes "holy shit, that computer guy just got the Bonecrusher on me." And nobody but the two of you has any idea that anything happened at all.