Tomei fell ill and had to cancel her slot on U.S. late-night show Conan at the last minute, and the host and his staff had to scramble to find a replacement guest.

Introducing Helms on his show, host Conan O'Brien said, "We had booked Marisa Tomei to appear on the programme; she was all set to come on the show... and then she called a few hours ago and said, 'I'm too ill, I can't come'. She has a bug of some kind, so our thoughts are with her.

"We call Ed Helms and say, 'Would you stop by and help us out?' The guy says yes and comes right over."

Helms joked he had nothing better to do, adding, "If you know me, you know that I'm terribly agoraphobic and I'm a shut-in; I was sitting on my couch with the curtains drawn, with (heavy rock band) Danzig on full blast, lights out, just rolling bong hit after bong hit... It's how I spend my time and it's important to me."

With nothing to promote and no time to prepare for the TV chat, the two friends chatted about what Helms had for lunch, his sleep patterns and his battle with a cricket in his house.

The funnyman then quipped, "There was one thing I couldn't move on my schedule, which was a conference call with Alejandro Inarritu, the director of The Revenant, so that call might be incoming at any time."

Helms then took the call on his iPhone and told Conan, "I'm in the sequel to The Revenant!"

He then got serious and added, "I am in a show which Alejandro Inarritu is directing. We're gonna shoot, hopefully, later this summer."

Helms then insisted on playing the clip for The Big Short that Tomei would have promoted on the show, adding, "Marisa, if you're watching, I love you, we're close, we actually worked together on Love The Coopers... so I have decided to see this clip."

The replacement guest then pretended he was Tomei and said, "(Co-star) Steve Carell was a nightmare (to work with). He keeps saying he loves his job (but) he hates his job, he hates everyone around him... The Big Short, obviously I'm so proud to be a part of this movie and I do think that the banking industry in America is really c**p."

He concluded his appearance by showing off one of his party tricks and spinning a book on his index finger.