Lauren Miller and Seth Rogen Lauren Miller and Seth Rogen

Seth Rogen told Conan O'Brien that his proposal to girlfriend Lauren Miller wasn't quite what he planned.

"The second I got [the ring] I walked right upstairs to propose to her, but she was in our closet changing and she was literally only in her underpants ...," said the 28-year-old actor, who's next starring in the film The Green Hornet.

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By the time he realized Miller was undressed, he had already begun the proposal and decided to continue.

"I didn't picture it like this, and I know she didn't picture it like this," he said.

Watch Rogen tell the story to O'Brien: