Asked by a news presenter about the frosty conditions for a TV vox pop on the weather, the schoolboy replied: 'Oh God you wouldn't be long gettin' frostbit.'
His thick Northern Irish accent was enough to prompt clips of the interview to be shared across the world within hours.
Soon the hashtag #frostibit was doing the rounds on Twitter, with users claiming the 18-year-old ad 'the best accent in the world' and using the word to describe chilly conditions in their own area.
Such was the response to the UTV clip, that the presenter who conducted the quick interview took to Twitter to comment.
Gareth Wilkinson tweeted: 'The 'Frostbit' boy I interviewed in Sperrins is Ruairi McSorley. That's how he talks you couldn't make him up.'
Later he wrote: '3.5 million hits and counting! Frostbit Boy Ruairi McSorley from Co. Derry is an overnight internet sensation @utv #frostbit'
Fans began creating memes.
One of the favourites added his quote to the emotional scene from Titanic when Kate Winslet is complaining of feeling cold.
In the short interview clip, Ruairi goes on to answer a question about having to go to school in the snow.
In an equally strong accent he says: 'We had to go anyway. We hadn't much of a choice in the matter.'
Since the broadcast, Ruairi has been enjoying his new-found fame and even returned to UTV for a follow-up interview.
The teen said: 'Oh God it's mad craic altogether. Imagine that!'
It seems this isn't the teen's first brush with fame. He has long been uploading videos of his impressions to his own YouTube channel and has aspirations of being a chat show host.
The talented teenager does impressions of a huge range of people from Dragon's Den's Hilary Devey to a spot-on take on Father Ted's Dougal McGuire, played by Ardal O'Hanlon.
He can even do an impression of a snooker match.
The YouTube video, which has almost 150,000 views, also shows the Irish impressionists doing his own take on Brendan O'Carroll's Mrs Brown, singer Daniel O'Donnell, BT voicemail and a host of Coronation Street characters.