Is it true that some job companies might reject you based on your Facebook profile?

[Lachrymose]

During High School (especially last year when I graduated), a lot of my teachers mentioned to us that some of the major companies might turn you down for a job request solely based on your Facebook profile.

Now, I myself have never applied for a job so far, but just wanted to know how true this is.

Has this ever happened to anyone?

Thanks!