Californian hip hop collective the Black Eyed Peas scored a global success with this song that questions the values of the modern world and the society we live in, and deals with issues such as racism, terrorism, pollution, gang crime, war, and intolerance. When hatred grows, and people and nations oppose each other, there's one question we find ourselves asking.

Leonard daydreams about saving Penny and her falling for him.

While Sheldon struggles with his take-out order, Leonard bids on what he thinks is a miniature time machine.

The boys decide to go to Long Beach in order to keep lying to Penny.

Penny tries to patch things up between Leonard and Sheldon when they are having a fight, but ends up making things worse!

When Penny dislocates her shoulder, Sheldon brings her home from the hospital and tucks her into bed.

Howard takes a moment in the tub to fantasize that Katee Sackhoff from Battlestar Galactica is in the tub with him. As it turns out, she has some advice for him.

Leonard finally tells Penny how Sheldon saved his life and broke the elevator at the same time.

When Penny returns from visiting her family in Nebraska, Leonard is happy to see her. Sheldon, however, is much less welcoming when he learns that her family has the flu.

Penny invents a quiz to find out whether Sheldon or Leonard is smarter, which only reveals that both of them are completely uninformed about popular culture with the exception of Star Trek.

In this short scene, a deeply star-struck Sheldon meets one of his heroes, the great actor James Earl Jones, whom Sheldon knows as the voice of Darth Vader in the Star Wars movies.

Wildlife caretaker and lifestyle photographer are among the jobs that were advertised in this promotional video for Australia. Each of the jobs had a nice salary and came with a jar of Vegemite, a spread made from brewer's yeast, vegetables, and spices, which is a favorite Australian food.

Released in 1968, the animated film "Yellow Submarine" was inspired by the music of the Beatles and featured them in person as well. The spirit of 1960s counterculture is well-represented in this trailer. Enjoy!

This video for the Beatles' song "A Day in the Life" features footage of the recording sessions which resulted in the song's famous orchestral component, as well as cameos by the Beatles and some of their friends.

"Hey Jude," from 1968, topped the charts in Britain for two weeks and for nine weeks in the U.S., where it became The Beatles' longest-running No.1 hit single. It was also the single with the longest running time.