When it comes to the idea of multiple timelines the Marvel Cinematic Universe gets a lot of credit; however, I attribute the origins of the phenomenon in recent pop culture discussions to something different.
If you are a fan of the television show Community then you are likely well-familiar with the episode Remedial Chaos Theory from the show’s third season. It is arguably the best episode that the show ever produced which is saying something.
No worries you aren’t a fan (HOW DARE YOU), I’ve got you covered. What you need to know is that there is a group of seven people hanging out in an apartment waiting on a pizza delivery, and when the door buzzes that the delivery has arrived, the group’s de facto leader suggests rolling a dice to determine who will go get it (after numbering each individual).