Commerce 40/80 - An LC hand and a question

[Dazarath]

Commerce 40/80
My normal game is 20/40, but I decided to take a shot last night because the 20 line was longer than the 40 line.

The villain in this hand is an extremely loose Mexican guy who calls too much on draws. Just for clarification, an underpair is a draw, as can be a single overcard. I saw both during the course of the night. Overall, I'd say he's a bit on the passive side. Here's the hand:

I am dealt A [img]/images/graemlins/heart.gif[/img] T [img]/images/graemlins/heart.gif[/img] in the BB. There are 3-4 limpers and the SB completes. Hero raises. All of the limpers call.

Flop: K [img]/images/graemlins/club.gif[/img] 3 [img]/images/graemlins/heart.gif[/img] 3 [img]/images/graemlins/club.gif[/img]
Hero checks. Everyone else checks.

Turn: K [img]/images/graemlins/spade.gif[/img]
Hero bets. Villain calls and everyone else folds.

River: 8 [img]/images/graemlins/spade.gif[/img]
Hero checks. Villain bets. Hero calls.

Now at this point, I'm looking at the guy waiting to see his hand. And instead, he gives me the same look as if he's waiting to see my hand. It's obvious my A-high is good and he doesn't want to show his bluff. The table starts to get impatient after a few seconds and the guy finally says, "Jack high". I turn over my Ace and this black guy next to me (he's really pissed at me because I took a large pot off of him a couple hands ago) says, "Show both cards of the winning hand". I show the second card in order to speed things up, plus, I know if he really wants to see them, he could ask anyways.

My question is, I thought the bettor was obligated to show his cards first. Is he allowed to just say "Jack high" and not show? Couldn't I just say something like "a pair of 8s" and then if they show a pair of 9s, I could be like, "Oops, I meant a pair of 10s", or if they show Js, then I muck? I understand that I could've asked to see his cards, but that's not what I'm interested in. I'm interested in standard conventions that speed the game up. If every showdown consisted of everyone waiting for everyone else to table their cards, we'd probably get a measley 20 hands/hour in. Lastly, if he says "Jack high" and I show an Ace and he mucks, is that good enough, or am I obligated to show the second card regardless of anyone else demanding to see it?

Sorry for all of my silly questions. As I'm sure any of you have guessed, I spend a lot more time with a mouse in hand rather than actual chips.