Bono and The Edge recently gave a special performance in McDaid's Pub in Dublin City Centre, which will reportedly feature in Letterman's St. Patrick's Day special about Ireland, set to be screened in the US on March 17.
The U2 members were joined by fellow Irish artists Imelda May, Brian Kennedy, and Glen Hansard for the special session at the Dublin pub.
Letterman's crew also filmed a special performance from Bono and the Edge in front of a select invited audience at the Ambassador Theater in Dublin on December 14.
Letterman has been in Ireland in recent days filming his St. Patrick's Day special, which is due to be released on a US streaming service, according to the Irish Independent.
Irish drag queen Panti Bliss shared a snap with Letterman and said, "He was interviewing me for a documentary, not sure when it’ll be out."
I don’t usually let any Tom, Dick, or Harry into my dressing room, but occasionally I’ll make an exception for a Dave pic.twitter.com/72NyktYoAb— Dr Panti Bliss-Cabrera (@PantiBliss) December 13, 2022
Earlier in his Irish travels, Letterman paid a visit to Badlands Vintage in Dublin, and had the craic with the shop's resident pup:
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Letterman also paid a visit to Cavistons in Glasthule, an Irish fish shop that has been in business for more than 75 years, on December 13.
Mark Caviston told the Irish Independent his father Peter was “delighted” to meet Letterman.
“We had a bit of fun with him this morning, he’s a very nice man," Mark said.
"He just landed out of the blue, sometimes you just don’t know who could come through the door, we heard about an hour before, so we got a bit of notice."
He added: “It was nice to see him, we grew up for years watching his show, you never think that these chaps will be out in Glasthule. I think he was touring the area, so he just popped in."
75-year-old Letterman is one of the most famous talk show hosts in history and presented his late-night talk shows - "Late Night with David Letterman" on NBC and "Late Show with David Letterman" on CBS - for 33 years between 1982 and 2015.
More recently, he has hosted the Netflix series "My Next Guest Needs No Introduction with David Letterman."
U2, meanwhile, were Letterman's guests several times. In one humorous appearance back in 2009, the lads took part in Letterman's "Top Ten" segment: