"Hey, wait, go back. Kill me again."

I was pranking my friend with the falling invulnerability I'd unlocked. I got it by base-jumping. You can open your parachute during a long fall and then try to steer yourself into a target area. He missed his target. I hit mine. As a reward, I got invulnerability from falling damage, no matter how far the distance. I am unbreakable, at least when it comes to gravity. But I didn't tell him.

Which is a good thing, because it's how I found one of the coolest features in Saints Row 2.

Read about it after the jump.

The next time he died from falling a reasonable distance – the characters in Saints Row 2 are a bit frail when it comes to falling – I told him he was doing it wrong. And I demonstrated by jumping down the same distance and getting up unscathed. I told him to try again. He did. He died. I revived him and told him he was doing it wrong and to do it like me. We'd go at the same time. He died. I told him he wasn't doing it right and to follow me more closely. I got a good five minutes of diversion from this, but no unlockables or gamerscore points. Like any good sandbox open-world, Saints Row 2 is good for this sort of goofing around. It's a big stupid fun playground and we're a couple of kids happy to fritter our time. I haven't had this much fun since Crackdown, where anything worth doing is even more worth doing with a friend. And anything not worth doing is probably worth doing if it's with a friend.

Once I told my friend that I had falling invulnerability, he cursed me a little and I shot him a little. But since he was still damaged from the fall, he died. I quickly revived him. That's part of what makes Saints Row 2 so painless in co-op. When your buddy gets killed, just run over, tap Y, and he's right back up again. There's none of this "falling back to the safe point" that makes Halo 3's co-op so often aggravating.

"Hey, wait, go back. Kill me again," my friend said.

"Why?"

"I got some kind of message. I want to see what it was."

So I killed him again. That's when we found Death Tag and Cat & Mouse. These are options in a co-op game when you kill your companion. The victim can press a button to activate either mode. Death Tag is a simply two-player kill-or-be-killed deathmatch, ranging across the entire city. But Cat & Mouse is one player in a Cobra attack helicopter hunting down another playing in a Lamborghini. The Lamborghini tries to reach as many checkpoints as it can while dodging missiles and gunfire from the helicopter. Once it's killed, the roles switch. He who gets the Lamborghini farthest wins. So we did these for a while and even got achievements for it.

Later, he and I would strip naked and compete in the prison's Fight Club, beating prisoners to death with our bare hands and the occasional hockey stick. The naked part was optional, but on a playground like this, juvenile things are particularly funny.