Justin Timberlake was back on Jimmy Fallon last night, either to continue promotion for The 20/20 Experience Pt. 2 or just because the two are coming dangerously close to becoming a comedy tag-team. The subject of the lecture this time around is hashtags, and how utterly moronic we would sound if we vocalized the tagged conversations we have online. Questlove, as always, is there to set the record straight. Stream the video above, but don’t you dare steal the #SexyGhost costume idea, that is mine.