There's a bromance brewing between Justin Theroux and John Krasinski!
During Jimmy Kimmel's post-Emmy Awards bash at a private members' club in West Hollywood September 23, the Your Highness actor, 41, and the Office star, 32, were spotted "dancing and singing" throughout the night, an onlooker tells Us Weekly exclusively.
Theroux and Krasinski -- sans respective loves Jennifer Aniston, 43, and Emily Blunt, 29 -- also chatted with fellow guests Josh Groban, 31, Ellen DeGeneres, 54, and Portia de Rossi, 39. At one point, a source says Theroux and Krasinski "were in a circle jumping up and down singing the end of [Carly Rae Jepsen's No. 1 smash single] 'Call Me Maybe.' It was hilarious!"
"Justin was having a blast," the partygoer adds. "After he had his 'Call Me Maybe' dance party, he hopped behind the deejay booth with Samantha Ronson and she gave him a tutorial!"
Theroux and Krasinski weren't the only A-list attendees at Kimmel's invite-only party. Guests including Twilight's Robert Pattinson, Breaking Bad's Aaron Paul, Modern Family's Sofia Vergara, Parks and Recreation's Aziz Ansari, Top Chef's Padma Lakshmi, Glee's Chord Overstreet, Missing's Ashley Judd, Happy Endings' Adam Pally, The Good Wife's Julianna Margulies, Saturday Night Live's Fred Armisen and Good Morning America's Lara Spencer sipped Don Julio margaritas and Bulleit Bourbon Old Fashioned cocktails; They snacked on Umami Burger sliders on their way out.
Host Kimmel, 44, "was having a great time," an onlooker adds. During the star-studded soiree, the talk show host "spent a while chatting with Jimmy Fallon."
At the end of the night, according to an onlooker, Krasinski gave Emmy Award winner and Modern Family star Julie Bowen a huge hug near the valet. "He told her, 'You're killing it. Keep doing what you're doing. You deserve it and I'm so proud of you.'"