Your friend left their game account logged in on your tablet. You noticed they had a load of coins and rare items you've always wanted. You could spend their coins, or use their account to enter a competition you're not old enough for, and they might not even notice for a while. It's right there, wide open, and they trusted you enough to leave it logged in. Nobody would know it was you — it's their account, their name. You didn't break in; they left it open. But "they left it open" and "they said I could" are not the same thing. The account isn't yours. The coins aren't yours. The fact that you could doesn't make it okay — and they trusted you.