Cup-stacking is a thing with the kids these days, and this song from “Pitch Perfect” is the soundtrack for it (music starts about 1:28).
David Letterman was quite impressed by Anna Kendrick’s cup percussion ability:
As someone who finds it hard enough to do one musical thing at a time, color me impressed as well.
That’s bloody impressive indeed. Keeping up the rhythm between hands and cup is good enough, but singing in tune and on key as well? Wow.