Rock, Paper, Scissors
How does paper beat a rock? It's stupid.
Rock, paper, scissors is a method that Sam and Dean use to delegate undesirable tasks. It's stated by Sam that Dean has always thrown scissors since childhood, and thus has been on the losing end of rock, paper, scissors his whole life. Dean, however, has beaten Sam twice at the game, the first in the alternate timeline Balthazar created by saving the Titanic, and the second on a qareen hunt years later.
Arguing over who is going to stay and keep an eye on Madison, Sam tells Dean they are going to settle it the "old fashioned way." Sam raises his fist for rock, paper, scissors and Dean plays along. Dean throws scissors, losing to Sam's rock. Sam remarks to Dean that he always picks scissors; frustrated, Dean wants the game to be best two out of three. Sam sighs as they lift their hands to play once more, with the same result of Sam's rock once again beating Dean’s scissors.
4.19 Jump the Shark
While helping "Adam" investigate what happened to his mother, they go to her house and find a vent big enough for a person to fit in under her bed. Sam and Dean look at each other, and they raise their fists for rock, paper, scissors. Sam picks rock, while Dean picks scissors as usual. Sam smirks as Dean waves his arms in frustration, remarking "every time."
6.17 My Heart Will Go On
In the alternate universe, Sam and Dean argue over who should tell Bobby to take a break from research. Neither wishes to do so, prompting a game of rock, paper, scissors. Dean, like in the original timeline, throws scissors, but in this universe he beats Sam.
7.12 Time After Time
After setting up in an abandoned house, Sam remarks that there is one "un-rancid" bedroom. He holds out his right fist on his left palm and nods to Dean. Dean assumes the position and the two hit their fist in their palms. While the outcome is not shown, Dean is once again the loser, exclaiming how stupid it is that paper beats a rock.
11.13 Love Hurts
While searching Sonja's hair salon for the qareen heart, Sam and Dean play rock, paper, scissors with the winner getting to search the upstairs and the loser the basement. First both throw rock, then both throw scissors. Then Dean throws paper to beat Sam’s rock, shocking both Sam and Dean. Happy that he just won, Dean doesn't even care that he somehow still ends up searching the basement.
11.16 Safe House
Sam and Dean do rock, paper, scissors to decide who has to paint a sigil in the soul eater's nest. Dean loses, leading him to remark that they should never settle things by playing that "stupid game" ever again.
15.13 Destiny's Child
When the Sam and Dean from the HunterCorp Universe become trapped between their and Sam and Dean's universes, they can be seen playing rock, paper, scissors in their trapped state. HunterCorp Dean also has an affinity for throwing scissors, which he loses due to Sam throwing rock in the first round. For the second round Dean throws paper, which Sam beats with scissors. Howver, Sam and Dean's reactions while playing rock, paper, scissors may hint the rules are different on their world.
The Winchesters Episodes
1.04 Masters of War
Carlos: What do I have to be in the bag?
Mary: Because you suck at Rock, Paper, Scissors.
Carlos: There is no logical world where paper beats rock.