Thousands of people shared an image of a building in Strabane which had the words 'Join the IRA' scrawled on it in black paint - only for a mystery man to edit it to read 'Join the library' instead.
Derry-born author and English teacher Brian McGilloway was first to notice the graffiti and posted the picture on Twitter.
"Got to admire the Strabane kid with the cultural conscience who altered 'Join the IRA' graffiti to this," he said, adding that it had brightened up his week.
We've never had a better advertising campaign ...
UTV later spoke to the man responsible for the literary twist, who confessed to not actually being a kid but rather a 28-year-old who was pushed into action by some rogue punctuation.
"I noticed the original graffiti on Tuesday and being a keen writer and grammar pedant, I was annoyed by the unnecessary apostrophe," Strabanksy said.
"Once I saw how library fit so nicely around the original tag, I felt compelled to change it.
"Strabane has an excellent library beside the Alley Theatre (I recently did a poetry reading there) - hopefully people take the advice and go and visit both premises."
Among the many responses were comments like "Books beat balaclavas" and "Pity there's not more like him".
But on Thursday, Brian McGilloway confirmed that the graffiti had been completely painted over.
"Like a Banksy, it should have been preserved," one Twitter user responded.