Aren't hashtags just the best thing ever? #NotReally. In Jimmy Fallon and Justin Timberlake's latest sketch, they speak in nothing but hashtags, somehowing end up following a hashtag with old-school Missy Elliott lyrics — you know the ones. Their comical conversation gets out of control, similar to an average Twitter and Instagram feed as they are clearly mocking the perpetual social media trend. But beware, MC readers: Excessive hashtagging is only funny when Jimmy Fallon and Justin Timberlake do it. So, unless you're the perfect Jimmy and Justin duo, singing your hashtags in unison, you should probably #QuitWhileYoureAhead.