I love The Hitchhikers Guide to the Galaxy, If you didnt know it is a comedy science fiction series created by Douglas Adams.
I've heard of it, but I've never seen it!  Is it really funny?
Yes its very funny and entertaining, In fact it was first a small radio comedy broadcast on BBC Radio 4 in 1978, it wasnt until later that it was adapted to other formats, including stage shows, novels, comic books,TV series, 1984 video game, and 2005 feature film
Wow, it's been around awhile!  Who stars in the tv show?  Anyone famous?
Yes, Martin Freeman and zooey Deschanel were two famous actors who played in the 2005 film adaptation. 
Oh I love Martin Freeman and Zooey Deschanel!  What's the plot of the show?  It sounds like it takes place in outer space?
Yep the show follows the misadventures of the last surviving man on earth, Arthur Dent, following the demolition of the planet Earth by a alien race called the Vogon constructor fleet in order to make way for a hyperspace bypass.
Wow, that sounds exciting!  Do the movies follow the same plot?
Yes they follow it somewhat, The main characters on the show are Arthur Dent, Ford Prefect, Zaphod Beeblebrox, Marvin the Paranoid Android, Trillian, and Slartibartfast.