THE BIG BANG THEORY fans love Johnny Galecki as Leonard Hofstadter, they might even remember him as David Healy from ROSEANNE, but do you know where he got his first big break?

He played Rusty Griswold, Chevy Chase’s son in the modern Christmas classic NATIONAL LAMPOON’S CHRISTMAS VACATION.

Fun fact, CHRISTMAS VACATION was directed by former Detroiter, John Hughes.

Don’t miss THE BIG BANG THEORY, weeknights at 7 & 10pm on CW50!