D.K.R.K.
Don't Keep Random Keys. If you keep a key, you're just making things harder for everyone else. Don't be a pain.
I found a key. I kept it. Now I have no idea where it goes. Everyone else is confused.
My friend found a key. He kept it. Now he's confused and I'm even more confused. Double pain.
You found a key. You kept it. Now I'm the only one who knows where it goes. You're a pain.