[extra88]

Yes, the particular phase "get a life!" was used against nerds, Trekkies, by William Shatner in a Saturday Night Live sketch [0]. It wasn't a new gag, but it raised the fandom's profile into the mainstream and it's often been repeated (e.g. on The Simpsons in Comic Book Guy and his cohort).

I assume the phrase was used here in the most generous sense but that's often not how it will be received. I think it's more constructive to avoid the phrase and to express the sentiment in other ways.

[0] http://snltranscripts.jt.org/86/86hgetalife.phtml

[brudgers]

It was in common usage where and when I grew up several years before Shatner on SNL. Whether my youth was at the forefront or not I don't know...but now that I have a teenager I know that many phrases he uses and thinks are new go back (at least) several decades to when I was the same age.