Headcanon that when Yang and Ruby were little and Ruby did something good Yang gave her a pat on the head. You got a A on your report card? Pat on the head. Wrote a little story? Pat on the freaking head. Killed your first Creature of Grimm? Holy hell your awesome another pat on the head.

But then one day one pat on the head gets too intense. its happens so fast. the patting increases. suddenly yang fucking pats ruby so hard she bounces and SLAM DUNKS HER LIKE COME AND SLAM WELCOME TO THE JAM