Why not make use of the carbonated soft drink itself?

Buy a new bottle of Coke/Pepsi and a roll of Menthos.
Dunk in 10 Menthos tablets or more packed in some water soluble packaging and close it super quickly because the reaction will start in 0.5 seconds or less if you don't.

Turn it upside down, shake it for additional effect and let it loose.

* If you dump in the 10 Menthos tablets without any packaging, you will get a volcano instead in 0.5 seconds.