Farkle
Farkle (also called Ten Thousand, Zilch or Greed) starts every turn with six dice. Ones and fives score, three of a kind scores, and you set scoring dice aside and keep rolling the rest until you stop or roll nothing that scores. That is a Farkle, and the turn's points are gone.
How likely a Farkle is depends on how many dice you are still rolling:
| Dice left | Chance of a Farkle |
|---|---|
| 6 | 2.3% |
| 5 | 7.7% |
| 4 | 15.7% |
| 3 | 27.8% |
| 2 | 44.4% |
| 1 | 66.7% |
The six-dice figure counts three pairs as a score, as most house rules do. Without that rule it is 3.1%.
Six d6 in D&D
6d6 is an 11th-level rogue's Sneak Attack. The full table, level by level, is on the Sneak Attack page.