be a thing (third-person singular simple present is a thing, present participle being a thing, simple past was a thing, past participle been a thing)

1. (stative, colloquial) to exist, or to be available, widespread, possible, or a common practice
   • 2014, Scott Haworth, Writing Journal: A Year in the Life of a Self-Published Author, page 36:

     So dinosaur porn is a thing now. I first learned about it on Kindleboards from a bunch of erotica writers who were very upset about the success of Christie Sims and Alara Branwen.

• See also Thesaurus:exist