This is all in humor. Really.
One child, tonight at the dinner table, started displaying this problem. When asked a question, to which the answer was no, he proceeded to swiped one finger across his face, drawing his head to the side. He let go and then wiggled his head side to side.
On the iPad, if it thinks you are moving an icon, all the icons will wiggle side-to-side until you hit the back button. My kids sometimes do this in error and have named that the "no" function because you can't do anything while the icons are "shaking their heads" back and forth at you.
So, after this, all the kids over 5 are now doing the one finger sweep across their face and the side-to-side wiggle to indicate no. iPad what have you done?