“The authors derive their inspiration from an Ig Nobel prize-winning paper describing a basic mechanical model that investigates the results of walking backwards while carrying a cup of coffee.”
So says the report “Mathematical model reveals solution to sloshing coffee,” in Phys.org.
The Ig Nobel Prize-winning paper about walking backwards while carrying a cup of coffee was itself inspired by an earlier Ig Nobel Prize-winning paper about walking forwards while carrying a cup of coffee.