You get the feeling that the group gambles due to boredom rather than any illicit or nefarious purpose. You doubt that they would cheat you but they definitely sense an opportunity to make some quick coin from an inexperienced gambler.
OOC:
The Rules of Three Kings
It is quite similar to poker but you roll three D6s rather than use a deck of cards.
The highest roll you can get is 3x3
Then it's 3 x 6s and then three of a kind in descending value.
The next highest rank is a straight of 4,5,6. Then it's a straight in descending order.
The next highest rank is 2 X 6s and then another pair in descending order.
The lowest rank is a single 6 and then a high single in descending order.
Those are the hand ranks. The real skill comes from insight and deception. A successful player tries to hide their hand so the opponent thinks they have the winning hand.
To play roll 3d6
Make a deception check to hide your hand.
Roll an insight check to guess your opponent's hand.
Betting continues until one player either calls or folds.
Does that make sense?