That’s the naughty little secret that former bachelor Colton Underwood reveals in his memoir  “The First Time.”

The former-NFL wannabe writes that “intimate moments included real physiological responses.”

“They weren’t on TV, but boners are a real, regular, and unavoidable part of the show. The producers are sensitive to guys who find themselves in a hard situation.”

The reality star, 28, says that a seaside frolic in Thailand with now-girlfriend Cassie Randolph swelled into a tumescent pickle.

Underwood writes that while splashing in the sea producers called him out for an interview but “I wasn’t ready to get out of the water.”

Thankfully, a producer picked up on what the dilemma might be and discreetly communicated to the crew that Underwood needed a little more time in the ocean.

Meanwhile, Underwood has fully recovered from his coronavirus infection. The reality TV star first disclosed that he had contracted COVID-19 on March 20th.

“Tested again and I now have the anti-bodies,” Underwood tweeted over the weekend. “I’m working with the doctor to find ways I can help donate blood for both research and other people.”