Pregnant Kaley Cuoco and her former co-star Johnny Galecki have revealed how they kept their off-screen romance a secret from The Big Bang Theory cast and crew.
The pair, who dated between 2008 and 2010, opened up about how they initially kept their budding relationship hidden from everyone and it all came down to sneaking into each other's room in the middle of the night.
Galecki and Cuoco - who is now expecting her first child with partner T om Pelphrey - said they decided to keep their romance under wraps during a group trip to Comic Con.
