.... And it explodes in your mouth and sprays everywhere.
This is the latest craze of my children. They saw it on TV, some science programme, and of course they had to try it!
First you take a few Mentos sweets - the more the better I believe.
Then you put all the Mentos in your mouth, and take a large swig of Coke...
When I think of some of the terrible things other mothers of 12, 15 & 18 year olds have to worry about, I'm so thankful that my biggest worry is how to get Coke stains out of a white sweatshirt!