A person outside the game looks at target opponent's hand and chooses a nonland card from it. That player discards that card.
You can choose any player not currently in your game. This includes people who used to be in your game but left it.
It doesn’t have to be someone who plays Magic. This may be fun.
If there’s no one around to make a decision, you can call or text someone if you need to. If there’s a physical action required, such as high-fiving, you’ll need someone there.