Omg.. it was so funny! We were practicing Front Kick to Chest and we were supposed to target the knot of the belt of the person we were practicing with. I did ok.. I was so careful to try and extend my foot that I was going too slow and not really snapping my leg out there. My partner did better, but she didn't extend her toes out so she kept missing. Sensei demonstrated on me.  Tap .. tap.. tap.. the ball of his foot tapping my belt.  Fine, no problem.. Then he says "And then if you want to extend". BAM!  He kicked me!   Not hard.. but hard enough to knock me back a foot. I grunted like a pig and then cracked up.. (but I can see where he could really really hurt a person)