Sister Math is very different from regular run-of-the-mill math. It's sort of like string theory is to algebra--it just operates on a very different set of rules. For instance, in Sister Math, the amount of times your sibling has done something is directly proportional to how much trouble they will be in when caught. They may have only done it two times if no one is ever going to know but that number can swell well into the double digits if mum or dad notices. 2 + 2 really can equal "ten times today alone" if the transgression is something like raiding the liquor cabinet.