During the opening number (“Bon Appétit”) on her Witness world tour, Katy Perry segued into the iconic Janet Jackson song “What Have You Done for Me Lately,” and, funnily enough, I don’t think the kids in the audience even knew the song, and if they did, they sure didn’t react in the same way I did (screaming, fainting, flopping around on the ground). Check it out below (“What Have You Done…” starts at the 2:39 mark, but the set design – with the Venus Flytraps and giant salt ‘n’ pepper shakers – makes the whole thing worth your while).