If he's shown a tendency to bet 10xBB preflop with rags, for sure I'd reraise preflop. If he hadn't been raising that much, and the JJ guy is worried about the maniac having a better hand or a coinflip, that makes the post flop play even more attrocious.

The JJ guy calls a $5 bet preflop with JJ, and then shoves over a $10 bet on the flop for a total of $26.5 (over 5x what he put in preflop). Its just a horrible horrible play, unless the maniac showed him his cards after the flop.

Shoving after the flop with A3 makes more sense (forgetting the preflop action - since clearly A3 shouldn't be in the hand), and I'm sure everyone can see that that wouldn't be a good play. Many beginning players really have a hard time forgetting the preflop value of their pocket pair on the flop. With this flop, its trash.