Gleeks, grab the tissues and the cocoa, because Kurt and Blaine just sang together again on a London stage.

Darren Criss' one-night-only concert at the Royal Albert Hall in London turned into a Glee reunion on Sunday, Oct. 18, when he surprised the audience by bringing out Chris Colfer to perform "Baby, It's Cold Outside," Variety reports. The song was an homage to their beloved characters, Kurt Hummel and Blaine Anderson.

As Us Weekly put it: "Christmas came early for U.K. based Gleeks over the weekend."

A solo that wasn't meant to stay solo

Here's how the magic happened. Criss began the song alone, telling the crowd he'd be singing both parts, even though "it's not supposed to be like that, but I've managed to pull off so many things," Variety reports.

A few verses later, Colfer joined him. And he arrived with the perfect entrance line.

The twist: Colfer's comeback line

"The only thing inappropriate about doing this song is doing it without me," Colfer joked before he started singing, as quoted by Variety.

Honestly? Iconic. Us Weekly reports that Colfer, 36, delivered the line as he hit the stage, and that Criss, 39, had started out telling fans he was comfortable singing both parts.

Why this duet means so much

Criss and Colfer first performed "Baby, It's Cold Outside" in Season 2, Episode 10, "A Very Glee Christmas," which aired in 2010, according to Variety. Their characters were fan favorites who began dating in Season 2 and went on to get engaged and married in the final season.

Fans have a name for the pair, too: "Klaine," notes BroadwayWorld.

The reunion came more than 11 years after the hit Fox musical comedy-drama wrapped. Glee first premiered in September 2009, Variety notes, and BroadwayWorld says the show concluded on March 20, 2015, after 121 episodes.

A little song history while we're at it: "Baby, It's Cold Outside" was originally released in 1944 by Frank Loesser, who wrote it for his wife, Lynn Garland, to sing with him, and it has been rerecorded by several artists over the years, Us Weekly notes.

Glee reunions don't happen often

That's part of why this one hit so hard. Us Weekly points out that Glee reunions "have not proven frequent." Before Sunday, Kevin McHale and Matthew Morrison visited Jonathan Groff backstage at his Broadway show, Just In Time, in January, and Jane Lynch, Amber Riley, Heather Morris and other stars joined Fox's Celebrity Weakest Link in September 2025, per Us Weekly.

For anyone who needs a refresher: Glee followed the New Directions, a glee club at the fictional William McKinley High School in Lima, Ohio, competing on the show choir circuit, and packed in more than 729 musical performances, BroadwayWorld says.

Where they are now

Life after McKinley High has been busy for both. Criss starred in 2018's The Assassination of Gianni Versace: American Crime Story and has performed on Broadway in Maybe Happy Ending, which he also produces, Us Weekly reports.

Colfer, meanwhile, has created the bestselling Land of Stories book series, along with other book collections, and is set to star in the upcoming film The Restoration at Grayson Manor, per Us Weekly.

About that reboot

And yes, Gleeks are buzzing about something else: last month, creator Ryan Murphy told Entertainment Tonight, "So, we have a script," as quoted by Variety.

Whatever comes next, Sunday night proved that Kurt and Blaine's chemistry hasn't gone anywhere, and we'll be replaying it all winter.

More concert and TV moments: see Miley Cyrus at the Hollywood Bowl, find out who's voicing Apu on The Simpsons now and get set for Abbott Elementary Season 6.