^^ its diet coke - Mythbusters did a s how on it

basically, the nucleation of the mentos ( it has hundreds of microscopic craters ) traps the soda bubbles - kinda like when you put a grain or salt or something in beer how it foams? same concept - atop of that, caffiene as well as a few other ingredients cause an intense nucleation acceleration, causing the big foam


oh and REPOST from like teh spring ( c'mon, MYTHBUSTERS did it )