When somebody messes with, bothers, or pokes fun at the person that they like in order to get their attention or a reaction out of them. Derived from how young children call their crush silly names or annoy them.
Jonah: Why does Ed keep messing with Aalia?
Ale: Oh, it’s the kindergarten rule. He messes with her to get her attention Jonah: *pokes Ale*
when one finishes using the bathroom and accidentally tucks their skirt down the back of their underwear (i.e. as a kindergartener would do unknowingly).