Shit happens

Shit happens is a slang sentence that is used as a simple existential observation that life is full of unfortunate unpredictable events, similar to "c'est la vie". The sentence is an acknowledgment that bad things happen to people seemingly for no particular reason.

It can also be said less vulgarly, including phrases such as "it happens" or "stuff happens".

History
The fact that people have been remarking that shit happens has been attested from 1964, when Carl Werthman quoted an example in his UC Berkeley masters thesis; the relevant excerpt was published in The American City (edited by Anselm L. Strauss) in 1968.

Examples of usage
In 2011, Australian politician Tony Abbott, who was at the time Opposition Leader and leader of the Liberal Party (later becoming Prime Minister), used the sentence in an interview.