Produce Etiquette

I have a burning question....

When you go to the store, what are the produce etiquette rules on grape bunches? Follow me here people. You go to the grape display and all the bunches are already put into bags with their little produce number on them. But the bags are open! Are you allowed to take out just one of the big bunches or just part of the grapes out and put it in one of those plastic bags on the roll that they have and take it to the cashier that way? But now it's missing it's little produce number. Or do you have to buy the whole thing? I mean, I don't want the whole thing and that's what you're making me do. That's lame. And why would they leave the bags open if I couldn't take some out? They would close them up, right?

And seriously, everyone does it with bananas anyway. You know you've seen those lonely bananas sitting on the shelf by themselves. They don't grow that way you know - in bunches of one or 2. Someone came along, decided the bunch was too big and ripped a few off. I applaud them. They are sticking it to the man. He can't make them buy more than they want!

But then again, I don't go and rip heads of lettuce apart. I buy the whole thing even if it looks a little big. I don't rip a few leaves off to cut it down to size. And come to think of it, no one else does either. You don't see 3 or 4 leaves floating by themselves. Hmm...this throws a wrench in things.

So what is the rule on grapes? Should I follow banana rules of etiquette or stick to the lettuce way of things? I'm confused.