Open up a two liter bottle of soda. Set it down on an even surface outdoors. Be sure not to shake the soda. It's not necessary to make it erupt.
Remove the Mentos mints from their paper roll. To get the soda to erupt at full capacity, you will need to get all of the Mentos into the bottle of soda, as fast as you possibly can.
Roll up a piece of paper. Stiff paper works best. Place it over the opening of the soda bottle. Make sure the Mentos mints can fit through the paper tube you made.
Drop the Mentos through the tube as quickly as you can. The soda will erupt fast, so you need to get the Mentos in and move out of the way of the eruption in a matter of seconds. Once the Mentos are inside the bottle, a blast of soda that shoots high into the air will be the result.