No, we haven't happened across some weird backstage party footage from one of Britney's Las Vegas residency gigs - she actually did this on television.

To be more precise, she did it on Jonathan Ross's ITV television show on Saturday night, at the TV host's behest.

Spears, to give her credit, went along with the whole thing and inhaled a whole balloon's worth of helium before singing a few bars of a song of her choice - which happened to be Taylor Swift's 'Shake It Off'.

Watch below: