Nearly half a million students on nearly 90 campuses have participated in the annual matching ritual since it first rolled out at Stanford University in 2017 as part of two students’ economics project. “The idea is, if you think about everybody who goes to your college, surely there’s someone who is a good backup plan for you,” said Liam McGregor, one of the students who came up with the pact. “Not a Prince Charming, you know, not your perfect person necessarily, but maybe somebody whose number you should have.”