adj. Of a word or phrase: short and memorable enough to be converted into a Twitter hashtag, possibly to the point of being dumbed-down or overly simplified.
2015
Shorthand for "downtown Los Angeles," DTLA has crept into the Angeleno lexicon over the last several years, a hashtag-friendly name that initially gained traction online and then bled into real life.
2014
Even if that's the case, networks can't resist cloning anything that's a hit on television, whether that's shows or campaigns. Given the success of both #TGIT and #WCW, they're all likely brainstorming hashtag-friendly campaigns in an effort to brand as many other nights of TV as possible.
2012
Newsweek magazine on Monday continued to display its unmatched penchant for creating hashtag-friendly cover designs — only this time, its intentions may have backfired.
2009 (earliest)
Wondering: will conference planners start considering what names might be hashtag friendly?
# are a topic convention/microtag. shows people your post is on/about x, plus gets picked up by hashtag friendly aggregators.