To pantomime means to act out or express something in an exaggerated fashion without speaking. You're trying to get the outside person to guess the creature based on your expressions and movements. You can't just point to the creature you want them to pick.

If the outside person chooses one of your creatures, consider briefly why you didn't fully explain to the outside person what's going to happen, and ask them to choose a creature you don't control.

Count the number of Robots you control as the ability resolves to determine how much damage to deal. If Ticking Mime Bomb is still under your control and still a Robot, it will count itself. Quietly.

You aren't allowed to speak while pantomiming, but you can explain to the outside person what's going to happen before you begin as long as you don't try to give them hints about which creature to pick.