First, to Mike: congratulations on finding the fun again... and good luck on dealing with that guy in the future. At 6th kyu, many of the suggestions will be difficult to put into play, so I'd work mainly on two that can be done at any level with equal ease: first, working with jerks can be a way to practice one's calm and communication skills. Don't worry about getting that particular technique, instead count it as a victory if your 'uhm, I'm working on XYZ right now, and it would really help me if you would grab softer/slower/etc' changes his behavior. Second, practice your ability to get those you want as partners: when a technique ends, run to sit next to those with whom you want to train. After the demo, quickly bow and ask them to be your partner. Don't sit on the edges. Don't wait to see who you will get.
Lyle, as for sincere atemi, at my first dojo we thanked anyone who hit us. Immediately. Getting hit a few times works wonders in teaching movement. I can usually get out of the way of a strike, but a funny thing happened in class the other night. My sensei, who is a large/powerful man, chose--- for God only knows what reason --- me as uke. Perhaps he saw me get out of the way of my partner's strikes earlier that night, and thought I'd move... On my part, sensei is always really cautious with female ukes, rarely uses us in techniques involving falls (especially female kyu students), so I was in for a surprise.
The technique he used for my shomenuchi attack involved a quick irimi and a shomenuchi of his own. Unfortunately, due to his speed and I think with his height his arm being enough above me that he found a blind spot, I didn't realize his move until I sensed his hand coming down on my head. I dropped down suddenly to get out of the way, and I guess this made him think he'd knocked me down hard. Now everyone knows my sensei is EXTRA EXTRA gentle with women, so this probably unsettled him. I saw the look on his face and thought 'oh great, I fell too soon, I must have prematurely ended his technique' and told myself, no matter how scary it might be (and it was
), to stand up longer. He, on the other hand, seemed to pull his next strike, just confirming in my mind he didn't want me to take a fall (when in reality, he was just trying to avoid hitting me). For the next few times he attempted to get me to fall without actually hitting me, while I kept looking at him pleading with my eyes "OK, I give up, what am I supposed to do" while ordering my body not to take the fall it was aching to take.
Over pizza later, we students decided if something like that ever happens again, it would be funny with the first strike to scream out then burst into tears. Of course, since that would permanently end any chances to take ukemi, it will bremain just a joke over pizza.