Look, if you feel that your friend is doing something wrong, then you should tell him, otherwise keeping your mouth-shut while you know about it, you'll be no better than to be his accomplice. I'll give an example of a situation I had to go through to convince how I feel about the packs being stolen or tampered:
Several months ago, I have been in a situation where my friend bought boosters from a retail store and found out that my friend planned to return them back (having the box re-glued) because figures that he pulled in the Force Unleashed set was crap. I felt terrible for the fact that my friend would ruin the fun pulling packs from people's hard earned money, the money where it's hard earned and deserved. I even explained to him that even it's not fair (but that's a part of life right?) that what he paid for isn't guaranteed to give you what you want, it doesn't give you the right to do what you did. And that's what boosters are made for, you'll pull something terrible, you have to stick with it because it's your fault for purchasing the booster in the first place, lesson learned (you get what you paid for, and people have been there). I pulled a Garm from TFU pack a year ago and I didn't mind, because what I paid for is exactly what I should get.
But he explained to me, "that there are too many selfish people around the world, why should I care about them, when people tend to screw you over? My other friend did it, but at least I'm not the one stealing figs, I just returned them originally in their packages exactly." It's a tough statement to answer, because half of it could be true about people's perception, but in most cases there are many people who aren't the same way. He is right that there are many selfish people, but it doesn't mean he should be one of them. Morality, you know it isn't right, but if you continue, are you no better than they are? He's the one that has to make a choice, around him and around many people's lives (especially younger players) that love to play and collect SWM, and not many people can be selfish about that. And just because your friend did it and you feel what you did is the right thing, does that make you a better person than your friend is? No, because returning something that you opened is no better than stealing something from a booster pack, because once you opened that booster... it's not a booster anymore, it becomes a tampered product ready to be hurt by someone's hard earned money. It's a toy for GOD SAKE, don't let it run your life to return it back, because you paid for that toy!
So because of the fact that I strongly feel I am against his ideals on tampering with products (and if it leads to stealing, I don't know) I decided to tell him straight in the face, that I won't be his friend anymore (and it hurts because I've known him and been his friend for years, but that's the sacrifice I'm willing to take to make my point across). Because I feel that if he doesn't support my ideology of doing things in a morality scale, he'll never understand what kind of person I am as a friend. I am not his friend's friend, and if he decided to be like that guy, I won't be there to support him, because I am everything that his friend is against... I believe that in order for your friend to make a difference, you as a friend have to justify it. Talking to a store owner about it would just make things worse because you as a person would "backstab" a friend, and it wouldn't be a friend in a first place. You have to tell your friend in the face, because if you strongly believe in something, you stick with it and you'll reflect on your friend's behavior.
But in time, things do change and I hope that my friend understands, that it's best that if he supports my idealism of morality, then he is considered to be my friend. Just as if you know your friend steals, it is up to you to convince your friend... your moralities, otherwise you're no better than he is.

so true XD

I dont get it.

Who was the injured party in all of this? The owner. I too advocate going to the 'friend' first. The best resolution is for the 'friend' to own it and pay for the booster...and I'm sure that there are ways to do that and remain anonymous. If he won't, then the owner must be told...or, using Eroschilles' idea, compensated. Speaking as one whose group lost their venue (Not through theft) it is difficult to keep a group going if you don't have a place to play. That's what will eventually happen if the owner decides that losses make the group a liability rather than an asset. So, even thinking from a purely selfish standpoint, it's better to let the punk who won't man up take the fall rather than the whole group suffering.