Kaley Cuoco on her recall of entire The Big Bang Theory theme: 'It took me 10 seasons'

Do you remember all the lyrics of The Big Bang Theory theme song? When appearing on Jimmy Fallon's Tonight Show and being requested by an audience member to sing it, actress Kaley Cuoco did not disappoint.

Cuoco, who plays Penny Hofstator on the show, took to Instagram to share a photo from the Tonight Show episode featuring herself with host Fallon. "Can't believe I remembered all the lyrics to @bigbangtheory_cbs theme song@jimmyfallon! It only took me 10 seasons!", she wrote in the post.

The first verse of The Big Bang theory goes:

Our whole universe was in a hot, dense state / Then nearly fourteen billion years ago expansion started, wait!...

The earth began to cool, the autotrophs began to drool / Neanderthals developed tools / We built a wall / We built the pyramids / Math, science, history, unravelling the mysteries / That all started with the big bang! / Hey!...

The 31-year-old actress also talked about the vacation she took with her boyfriend Karl Cook and his family around New Year's, which according to her, felt more of an extreme date on The Bachelor than a family getaway.

Cook and his family took Cuoco to New Zealand for the holiday, where one of their planned activities was a canyon swing. Cuoco told the host, "I felt like I was on The Bachelor. 'Can you jump off with him? This is the next step in your relationship.' I'm like, 'Am I gonna get the rose out of this?'"

The actress didn't back out, buckled into her harness and jumped off the side of a mountain, free falling for a few seconds before they eventually got to the swing part. "It's a bungee jump and if my boyfriend calls it a swing one more time, I swear I'm going to kill him. You dangle and you hope that you're going to see your family again," she said.

"It was horrible. [But] I got the rose," the CBS star added of her experience.