Every time I have a party, I spend an hour building a playlist, imagining my guests all gasping and dancing and reaching for Shazam. Instead they ignore the music until someone takes over the Bluetooth speaker. So I asked for help from university student Tj Jones, who had a viral tweet this February when he shared the 11 playlists he used to categorise all his Uber and Lyft passengers, such as "quiet ppl" and "white dudes who look like they like rap".