Leprechaun Will Ferrell sings Danny Boy for St. Patrick's Day

When Will Ferrell swapped his 'Elf' costume for a leprechaun one ahead of St. Patrick's Day.

Buddy the Elf, who? Leprechaun Will Ferrell donned his bit o' green while singing a rousing rendition of 'Danny Boy' during a St. Patrick's Day appearance on 'The Late Show with Dave Letterman,' in 2015.

“St Patrick's Day is a really serious holiday to me," the Irish American funnyman told Letterman.

"We know of it as getting drunk and drinking green beer. But we forget in the 15th century, the real St. Patrick chased all the snakes out of Ireland. So, every St. Patrick's Day, I put on my outfit and walk the streets of New York educating people on the dangers of snakes."

If you thought you’d escape Paddy’s Day revelries without a hint of 'Danny Boy’s' pipes calling, Ferrell hops in with his newly reworked rendition – “Danny Boy...Watch out for snakes,” outlining the no-go snake hiding holes in New York. I think we could have a "Danny Boy" revival on our hands.

You can catch a glimpse of Ferrell's hilarious interview starting from 2:58 here:

He was also joined by co-star of his movie, Kevin Hart, to send the Irish people some further good advice on staying sober this St. Patrick’s Day. With their perfect rendition of the Irish lingo, Ferrell and Hart could be mistaken for natives.