Do you have a tic?

I stim, if that counts.

Does masturbation count?

I take medication for EPSYLIY.

No but bed bugs seem to be running rampant.

Sometimes if I sit too still, my left hand or leg will twitch.

I get them on occasion. Usually, it happens to my leg if I'm sitting down but once, my right eyelid wouldn't stop twitching and it was so uncomfortable:/

Yes, I stim which sort of means sometimes my hands flap around on their own accord but its hard to explain, I have no control over it. and I also pick the skin around my nails. It sounds like just a bad behavior, but I always do it in response to anxiety and stress. The worse the anxiety is, the more bloody and horrifying my fingers look. I also will quote movies and songs and say things over and over to myself because it helps calm me down. For instance, right now, "In heaven, everything is fine" and "It's my chocolate attack!" are the two quotes I've found myself using most often (Both are from songs). Sometimes just to fuck with my cats I'll just razz them and say "it's my chocolate attack!"

Do you have turrets syndrome?

SPOOOOOOOOOOOOOOOOOOOOOOON!

Oh? Not that kind of Tick? What have I done?!
http://1.bp.blogspot.com/-gxdUXzxcleA/TbUHFdWIwvI/AAAAAAAAAFk/tuUst1gfuaI/s1600/tick.gif

Not unless you count blinking, which to be fair does seem to fit that description. But I doubt you do, because then everyone would have one :P

Most ppl do, without knowing of it.
In a psychologist eyes, that's called touretssyndrome, perfectly normal.

My left eye twitches slightly when I'm tired or nervous.

Eh. I get shivers out of the blue sometimes regardless of temperature. Maybe a few times a week.

Only really rarely, like when my leg jumps for no reason. Although if you count voluntary tics then I do find I have to move my body about every five seconds when I have insomnia. I simply can't stay still.