Not the kind of thing I usually go in for, but let's give it a whirl: idea stolen from
tooth_fairy.
You comment here. I pay you a compliment.
The first rule is that you must accept the compliment. No trying to wiggle out of it.
The second rule is really more of a suggestion: If you see someone you know in the comments, it'd be awfully nice if you paid them a compliment, too. This is optional, of course. But it would be nice.
Edit: I'm at work, I'm quite busy. So I might not get round to answering for a while. This isn't because I'm thinking holy crap, how do I say something nice about that total failure who just commented ;)