To start, each person gets a score sheet to keep track of their points throughout the game. (There are variations to these rules, but this is how I play...)
(This is the one I designed to match my party scheme.)
Everyone sits at tables of four and each person is paired up with the person across from them (for this round only). You start with "ones" and the first person rolls 3 dice in the attempt to get as many 1's as possible. One "1" gets 1 point, two "1's" gets 2 points, three "1's" is a BUNKO and is worth 21 points. You roll until you no longer get any 1's, keeping score with every roll, and then you pass the dice to the person on your left. The only exception to this is if you get three of any number other than the one you are attempting to get (1's in this case), then you get 5 points, and you still get to keep rolling. The person to your left now attempts the same thing. Your partner's points and your's are combined together to create your team score. If you score a BUNKO, those 21 points go towards your team points, but only you get to claim the BUNKO as your own. This is important when it comes to prizes at the end. Just mark a tally on the BUNKO line at the bottom of the score sheet.
Dice are being rolled simultaneously at all tables around the room, as players at each table are trying to get as many points as possible In the meanwhile, there is a head table who is controlling the pace of the game. They ring the bell to start, and when one of the teams at the head table rolls either a BUNKO or achieves 21 points, they ring the bell again to end the round for everyone.
Each team will compare their points to the opposing team's points. The winners will place a "W" by the first column's "1" and each person on the losing team will place an "L" on their line. The losers then stay at their table, but one person switches seats so that they are no longer on the same team. The winning team of each table rotates to another table, also switching seats to have a new teammate. However, at the head table, it is vice versa. The winning team stays and the losing team moves on to the next table in the circle.
When the head table rings the bell to begin the round, everyone starts rolling for "2's". Again, one "2" is one point, two "2's" is two points, three "2's" is a BUNKO, and three of any other number is 5 points. The round continues as the previous one did. And, when the round is over, each table rotates and repeats the process for "3's", then "4's", "5's", and "6's". After all 6 rounds, you can choose to start at "1" again, and most groups seem to do this 4 times, according to the sources I found while trying to refresh myself on the rules.
Once your group has played as many times as their hearts desire, each person needs to tally their wins, losses, and BUNKO's. Then the host awards prizes to the person who scores the most wins, the most BUNKO's, and yes, even the most losses! It's a fun way to ensure that everyone has fun, and even the sucky players can walk away with a prize! Some groups play for money, where each person in the group contributes an amount and it goes into the pot for the winners. However, in my experience, the host just provides fun goodies (like thermoses or soap sets or cooking utensils).
The game is fast-paced and high energy, not to mention a total blast for everyone who plays. I've done it both as a youth group full of teenagers at church and as a women's night out with adult ladies of all ages.
Right now, I'm working on making the prizes for my upcoming party's BUNKO game. Stay tuned to see what I'm giving away!