And then they went on to make fire and invent the wheel...
When men greet each other (usually in social situations, occasionally in casual professional surroundings) I notice the high-five/handshake hybrid, followed by pulling in for the forceful hug/one hard smack on the back.
Do you know what I'm talking about?
Where did this behavior originate? Do you need a Y-chromosome to understand this? Each time I witness it, it freaks me out a little bit, and seems uncomfortable.
With a measure of brute force, it seems to say "nice to see you, I'm straight, see how strong I am?"