[bolgenmod]

There have been a billion posts (only a slight exaggeration) about this in 2+2 B&M about people not showing hands, others wanting to see hands (IWTSTH -- I want to see that hand -- is the abbreviation usually used), etc. It also comes up all the time in the 2+2 home game forum.

At most casinos, you have the right to see the hand at showdown. Some casinos have instituted the rule Space mentions: they will actually ask you to say why you suspect collusion, and if you don't suspect collusion, you can't see the hand. At other casinos you will be shown the hand if you ask. The original intent of the IWTSTH rule was to prevent collusion, but since so many players now are using it for information (and many players get really annoyed at the request), some casinos have added that rule.

But the basic thing is this: in most casinos, IWTSTH is considered a nitish and/or a d!ckish request. It can be seen as implying cheating of some sort, so you basically don't want to do it when up against a good player. And when against a bad player, you don't want to tap on the glass after all.

Home games are, of course, different: there it depends on the game and the players. I've shown my hand at a player's request, but I also mentioned that the request implies that I am cheating, which meant that that was the last time anyone asked to see anyone else's hand. (They think I am a total poker geek, but they also know I know the rules better than they do.)

In almost all cases, I just table and declare my hand no matter who bet first when, because I want to get on with the game. At the casino, I will wait for the aggressor or the earlier position player, but only if I really think I am beaten and only for a few seconds. (I once tabled and declared "busted flush" when in early position on a checked river -- my opponent then complained "she doesn't have the flush"! Practically the whole table chorused: "she said BUSTED flush.") If someone shows a better hand, I muck. And if they ask to see my hand, I take note of that player: they are usually not as good as they think they are.

If you want rules, the rule is as others stated: earliest position (or last aggressor in some casinos) shows first on a checked river. And yes, you can ask to see the other person's hand. But it is at least considered bad form and can be seen to imply something worse. If everyone would just go ahead and just table their hands....