Hashtagging is so popular on social media now that it almost constitutes its own sub-genre of comedy. But instead of practitioners standing up in front of a hundred people in a bar or club, hashtag homorists sit down with their laptops, tablet and smart phones to make people laugh all over the world.
Needless to say professional comedians love this game, and often contribute the most retweeted tweets. But they don't dominate entirely. Sometimes the very best of them come from people who have no aspirations to be professional funny men and women. So it's a real meritocracy in this regard.
But if you are either a professional or aspiring comic, then getting into hashtagging is a good idea. The challenge of creating relevant, funny tweets for the hashtags suggested is a good writing exercize apart form anything else. And some of the lines you submit as tweets could no doubt be turned into gags you could perform live. In a way, you've already tested them out, because they've been seen by many people already. The ones that get a lot of reaction online in the form of retweets and mentions will be much more likely to elicit laughter from a live audience.
As well as the practice the activity gives you, it's also a good way of lifting your profile. Get known as an accomplished hashtagger and this could have benefits for your live career because more people will have heard about you, as well as being acquainted with your comedic style. Considering how many people use social media, odds are that persistent hashtagging will get you known by more people than live gigs (with the exception of TV, of course).
Regardless of whether you contribute your own funny hashtags, just noting them gives insights into comedy. For example, you'll notice how so many of the hashtag suggestions involve widely known popular culture references such as celebrity names, movies, TV shows and hit songs. These are paired with incongruous elements to inspire lots of creations that the greatest possible number of people will find funny. Examples include #ElderlyTVShows, #ShartCelebs, #AlcoholAFilm and #RejectedTVShowNames. This basic structure can be of use if ever you are at a loss for ideas for comedy material.