The 38-year-old actress and her husband Jerry O`Connell have two-year-old twins Dolly and Charlie and they have to constantly keep an eye on the girls as they are not afraid of anything.
Rebecca said: "Charlie, since she was a baby, if I get dressed up for something, she`s the one who looks me up head to toe, checks out my shoes, takes it all in. Dolly`s never noticed.
"Dolly`s like, `Where is a giant piece of furniture I can stand on top of and almost die?`
"I feel like we`re getting through the death watch period where they might almost die, but hopefully we`re going to start communicating and explain why you can`t stand on that really tall piece of furniture."
Because of their fearless nature, Rebecca is reluctant to go out alone with the twins, though she admits their father copes much better when they are out and about.
She added in an interview with TV talk show host Rachael Ray: "They`re at this age where they run off in opposite directions from one another, so I`m still not really brave enough to take them out alone by myself because you can-t run in two directions.
"And if you`re in the middle of the parking lot and they both just drop dead weight - Jerry`s big enough, he`s brave enough, to scoop down and pick them both up, but they`re getting to be big people!"