A social science best described as the study of how environmental stimuli influence
an animal's behavior. Fundamental concepts such as Pavlovian Conditioning and Instrumental Conditioning are the basic Principles behind
learned behavior and can be used as one method of explaining any kind of behavior.
Psychology is one of the easiest ways for a slacker (like me) to obtain a B.Sc. without concern for
natural sciences like Chemistry, Calculus, Physics et c. It's legitimacy is apparently controversial, judging by the other definitions listed, but let's not forget that this is URBAN DICTIONARY.
It is true that many students major in Psychology, and they're also the ones you'll find in some Pub during midterm week because they got their studying done early. Not all Psychology majors want to be shrinks, some just want to get a degree and get the fuck out with as little effort as necessary. Isn't that what University has become these days? A B.Sc. is, after all, a B.Sc.
Example:
Guy one: Hey man, what did you
think about that Psychology class?
Guy two: Good enough. Let's go get a beer and a burger and then we'll party in the
dorms.
Guy three: okay, fuck those med students man, not everyone is cut out to be a doctor.
Guy one: yeah, I'm a lazy piece of shit.
But whatever.