Kaley Cuoco, Johnny Galecki talk about 'secret hotel room romance'

Kaley Cuoco and Johnny Galecki hid their love from The Big Bang Theory cast and crew.

The couple, who dated for two years, kept their relationship under wraps in the initial phases.

Cuoco told Us Weekly : "We all had different hotel rooms at Comic-Con. There were two giant buildings for this one hotel and Johnny and I weren't even in the same building.

"So we were like little mice in the night, running back and forth to each other's rooms, trying not to be noticed. I mean, who did we think we were?"

Galecki added: "So we would all be in the hotel lobby... and Kaley and I would give each other a hug and pretend to say good night, and go our separate ways."

Cuoco said: "This is charming looking back, but I was on a shuttle bus with the cast and I was sitting next to Kaley trying to strike up a conversation.

"The best I could come up with was, 'So ... what's going on with you? You got a fella? You seeing anybody?' Like, I'm her dad or something.

"And she starts giggling and says, 'Oh my God, you don't know?' And I said, 'I don't know what? What don't I know?' And she says, 'I'm seeing Johnny."

The pair broke up in 2010 on good terms.