Emoticon facial expression recognition
Python, 86 bytes

I should be sent to prison.

x=lambda c: ["happy","sad"][c[0]+c[-1:]in open(__file__).read(88)[::-1]]#&lt;][&gt;&lt;:&gt;{:}(:)


The shortest I could come up with was equivalent to Martin's CJam answer, so I decided I'd hide all the sad emojis (minus the middle character if any) in the reverse of my code and use Python's __file__ quine cheat.

Muahahaha.