Sorry for the editorializing, but this is my term for a common phenomenon in roleplaying games which create their own systems. Every game wants to give you an exciting new way to roll dice, just to add a cheap and easy "sub game" to the RPG itself. For this writeup, I will call something like "Strength" a trait, and something like "Open Locks" a skill. Every system has its own names for everything, just as every system has its own dice rolling system.
The first one I encountered was the White Wolf (originally for Vampire: the Masquerade). In the White Wolf System, you roll a number of d10s equal to skill + trait, and when you roll a 0 on the die, you roll ANOTHER die. So, rolling two dice, you could theoretically have "four successes" (if both dice came up 0s the first time). If you roll a 1, you remove a success. If you roll more 1s than successes, you've botched and bad things happen. (But at least all their systems use the same dice rolling mechanic.)
Shadowrun has a similar trick, if you roll a 6 on the d6, you reroll that die and add the previous result. So, if you roll a 6, and roll another 6, and then roll a 2, you've rolled a 14 on that die. (Shadowrun has a similar concept of skill + trait). If you roll all 1s, and only if you roll all 1s, you've botched.
Ars Magica is crazy in that it has three different systems in the game itself. It has the simple roll, the stress roll, and the quality roll. The simple roll is just roll a d10, add your skill and trait, and that's the total. A stress roll is if you roll a 0, it's a botch, if you roll a 1, reroll and double the result, but now a 0 counts as a 10. The doubles are cumulative, so you could theoretically roll a total of 144 on a single d10. And finally, the quality roll is a stress roll where a 0 is always counted as a 10.
Legend of the Five Rings and Seventh Sea share a system with some unique concepts. Roll a number of dice equal to your skill, discard all of the dice except for a number equal to your trait, and then total them up. The special thing about rolling a 0 is that you can now roll *and keep* another die. (Basically, if you roll a 10, roll another die and add ten to it. I think they describe it as "reroll 10s, and add 10 to the roll" but it is easier for me to count dice, than it is to remember what I rolled.)
John Wick also put an even more complicated mechanic in Orkworld, which I never entirely figured out (something about not being allowed to keep the dice equal to the rating of your weapon or armor). Changeling the Dreaming (first edition) almost resorted to a card-game mechanic, instead of dice tricks, for its magic resolution. And I'm sure that out there, someone else will think of a new way to roll dice.
All I know is that every new game, I don't look forward to playing an odd form of craps. The "reroll 10s" makes it harder for me to do the mental statistics in my head to calculate success of an action. It makes me long for playing a good game of GURPS or Dungeons and Dragons/d20 System. This is one of the strengths of the d20 System in that you don't have to relearn how to roll dice.
Let me state for the record: I only mentioned games I have familiarity with and loved. So, I mention Shadowrun, Ars Magica, D&D, Vampire: the Masquerade, etc because I loved the system enough to have learned the rules. This node is a reaction to the fact that each time I learn a new wonderful system, they don't attempt to build off of each other's shoulders, they attempt to rewrite the entire world. Please, oh all you makers of RPGs, accept that your competitors are smart fellows who know what they are doing: Reuse some of their good ideas! Thank you kindly!