India, Oct. 22 -- Students at Scotland's University of St Andrews took part in an unusual annual tradition this week, turning a campus lawn into a shaving-foam fight. Dressed as sunflowers, Smurfs and other quirky characters, hundreds of students gathered for Raisin Monday, a centuries-old university ritual.

While the sight of students covering one another in foam may seem unusual, the tradition has a curious backstory.

The tradition at the University of St Andrews dates back around 600 years. First-year students traditionally thanked older students who guided them through their first weeks at university by giving them a pound of raisins, which explains the name Raisin Monday.

Over time, the custom transformed into the shaving-foam spe...