Reilly also revealed that he thought he had a nervous breakdown on set: "I got home and I stopped drinking four pots of tea a day and I was fine. Turns out it was all the English tea."

Will Ferrell and John C. Reilly visited Jimmy Kimmel Live! on Wednesday. The actors, who wore matching suits, reflected on filming Holmes & Watson together in London.

Kimmel asked how the actors decided who would play Sherlock Holmes and who would play John H. Watson. "At first we couldn't, so we'd shoot every other day switching parts," joked Ferrell. "It was so cool. We have a full month of us switching. It was not cost-effective."

He continued, "I decided to be Sherlock. John is the amazing Dr. Watson."

"In Step Brothers, I lived in a house of learned doctors," added Reilly. "And in this movie I get to play a learned doctor."

Reilly revealed that he thought he had a nervous breakdown on set. "I thought, 'I'm having a psychotic break. I won't go see a doctor here. When I get home, I'll see a psychiatrist 'cause something is very wrong,'" he said. "I got home and I stopped drinking four pots of tea a day and I was fine. Turns out it was all the English tea."

Ferrell added that he drank "plenty of tea" while in London, though he had no problems.

Reilly also shared that he lived on a houseboat while filming the movie. The two explained that the unsteadiness of the boat would often get in the way of their social gatherings. They stood up and knocked into each other to visually explain what would happen when a large wave hit the boat. "It felt like you were drunk all the time," said Reilly.

Kimmel then shared a photo of the two at a soccer match. In the photo, Reilly wore a tweed suit while Ferrell wore a suit and tie. Ferrell said that they dressed up because they were "in a special area where you had to be formally dressed." He joked, "Of course I'm wearing a speedo underneath it." Reilly added that they ran into Mark Strong at the game, who played Lord Henry Blackwood in the 2009 film Sherlock Holmes. "So we're talking to him. He's with his son. We take a photo with him, absolutely. He's like, 'What are you guys doing here?'" recalled Ferrell. "We're like, 'We're doing Holmes & Watson. And he went, 'What?' And he just had this astonished look. I don't know if it was anger. I don't know if it was jealousy or resentment."

"I think it was disappointment," added Reilly.

The two then reflected on their friendship and their previous work experiences together in Step Brothers, Talladega Nights: The Ballad of Ricky Bobby and Anchorman 2: The Legend Continues.

"I did like Will right at the outset. I'll never forget [we met] on the West Side Highway. Molly Shannon introduced us and I was like, 'Who is this guy? He seems very familiar, like we could be related or something,'" said Reilly. "Over time we got to know each other better and better and then I almost did Anchorman — it didn't work out — and then eventually we did Talladega Nights together, and I feel like we did develop quite a real relationship."

"One of the things I love about John is he has colorful expressions to announce when he's going to the bathroom," added Ferrell. "It's become one of my favorite terms, as well, that when John has to go number two — which can also mean, you've heard the term 'drop a deuce' — he just says, 'Guess what? I got to find my passport — it's somewhere here — 'cause I'm taking a trip to Dusseldorf.'"

He continued, "On a film set, that just gets shortened to 'You got my passport?'"

Later in the appearance, Ferrell and Reilly sang Peaches & Herb's "Reunited" together.

When Kimmel asked how it felt for the two to reunite onscreen, Ferrell became emotional and pretended to cry. "I got a lot of emotions," he said.

The host said that they could take a break to calm down after the emotional moment, though Reilly suggested that they sing about it instead.

"I was a fool to ever leave your side," sang Ferrell and the two men grabbed microphones and stood up. "The breakup we had has made me lonesome and sad / I realize I want you, want you bad."

"I spent the evening with the radio / Regret the moment that I let you go," sang Reilly. "I know now that I love you 'cause I miss your touch."

The two then turned to each other and sang the chorus in unison. "Reunited and it feels so good / Reunited cause we understood / There's one perfect fit / And, sugar, this one is it," they sang. "We both so excited cause we're reunited, hey, hey."