That wouldn’t work, the water would change the texture of the mentos before the soda hits it.
Ok ok, plan B then:
We freeze the end of a rope in ice that they unknowingly throw in their drink. The other end of the rope holds a bucket of water above the chair they sit in. Once the ice melts, the rope will slip out and the water will come down on them. They will never know what happened!
Even if it didn’t change the texture, it wouldn’t be a sudden explosion, but a slow release. The ice would melt off, slowly exposing the surface of the Mentos. To get the explosion they want you have to throw the Mentos in quickly.
What if you had piece of ice with an air cavity where the Mentos is placed, then sealed in? I think that might work, bit it’s certainly tricky to set up.
Smh soda needs to get on board and stop being a little bitch with its soda-tongue pickiness. Try something new, soda.