Forum:Spirit Reaper Discard Method

Hello, I posted this in the Rulings sections but I didn't get any feedback, I think I posted in the wrong section perhaps? So I'll try here:

In the end part of Spirit Reaper's effect it says "...your opponent discards 1 card randomly from his/her hand." So my question would be: What is the best possible method to have your opponent discard a card from their own hand at absolute random?

If they shuffle it themselves, they will innately know at least one card simply by human instinct, especially if there are a small amount of cards. Since they know, it is in no way random.

So would the best way be that I (without looking) shuffle their cards for them, and they randomly discard, then I (without looking) hand their cards back? Or would it be reasonable for me to just randomly choose after I inflict battle damage?