"Breaking Bad" star Bryan Cranston opened up about an embarrassing situation on “Conan” on Thursday where he explained to Conan O’Brien how he and his wife got caught having sex on a train from Switzerland to Italy.

Bryan Cranston and Robin Dearden on honeymoon

When Cranston and his wife Robin Dearden tied the knot in 1989 they went on a European honeymoon. When they wanted to travel from Switzerland to Italy, their travel agent suggested that rather than going over the Alps, they should catch a train. Before boarding the train, their travel agent told them an unusual fact about the particular mode of transport.

Cranston explained to O’Brien that the agent said the third tunnel takes the train 50 minutes to pass through and that it’s very dark. The agent said it is a tradition for honeymooners to "take advantage" of that fact. Cranston said he understood immediately, saying to the agent, “Capiche.” He said to his wife they were doing this, asking her if she was ready to “use up seven calories.”

Traveling on a train in a car

It turns out the train doesn’t carry only passengers, but also their cars on a flatbed carrying three vehicles, bumper to bumper, which he said was something like a ferry.

Because of that Cranston and Dearden decided to stay in their vehicle for the whole journey. There was a van full of kids in front of them and two Italian couples in the car behind them.

Sure enough, when the train entered the third tunnel it was as dark as the agent had promised. Cranston described it as “an absence of light,” saying you couldn’t even see your hand in front of your face.

He said he found it exciting, with the wind rushing next to them. While explaining what he did in more detail, he said the car was very small and had a stick shift – he gave others advice on keeping their pants on before climbing over to the other seat, due to, um, some discomfort he experienced.

They then went on to make what O’Brien described as the “beast with two backs.”

Agent may have been playing a prank on Cranston

Maybe the train didn’t take as long as 50 minutes to pass through the tunnel, or possibly Cranston and his wife had extra stamina, but he said it seemed like a very short space of time before he started to see his beautiful wife’s face. He said at first he believed he was just getting acclimated to the darkness, but then said the train suddenly came out into “broad daylight,” and that he and his wife were completely naked. He said with his positioning, he found himself staring right at the people in the car behind them.

According to Cranston, children in the car in front were turning around and staring, while their grandmother was saying, “No, no,” and glaring at him in total disgust.

He and O’Brien agreed that just maybe the travel agent had played a prank on him about the 50 minutes. Cranston said the experience didn’t have a happy ending, as his beautiful wife said the three words you really want to hear on honeymoon, “Get off me!” Enjoy the story with more detail in the video below.