Sarcasm

Though they may not be aware of it, sarcasm is their means of indirectly expressing aggression toward others and insecurity about themselves. Wrapping their thoughts in a joke shields them from the vulnerability that comes with directly putting one's opinions out there. "Sarcastic people protect themselves by only letting the world see a superficial part of who they are," says Steven Stosny, a Washington, D.C.-based therapist and anger specialist. "They're very into impression management."

(emphasis mine)

Examine your motivations.
Some people resort to over-the-top sarcasm in an attempt to shore up their own self-image. Consider whether you yourself harbor feelings of inadequacy. Once you feel comfortable with who you are, you won't need to hide behind a veil of sarcasm.