A phrase meaning the mental process you use. One thing triggers another thought on and on until you say something random, which is only percieved as random by others not in your head. Also can be used when you pause after a joke or something along those lines and then finally understand it.
Lola- We have to do a project on a country for history. What do you think I should do?
Biore- Hm.. I really want a potato
Biore- I was playing hopscotch in my head. I thought of countries and I thought of Ireland. I thought of Ireland's famine and how they had to eat potatos. That made me want one. Not random at all!!
Emma: And the blonde thought the directions were wrong on the Kool-Aid packet, because you can't fit 4 quarts into that tiny thing! :]
Claire: pause..................OMG lol!
Emma: Um..you're so stupid that took you forever to get!
Claire: Shut up! I was playing hopscotch in my head. Duh!