Lil' Sis' Amazing Talking Hands

Lil' Sis talks with her hands. I don't mean a gesture here and there to make a point, but a full-blown, hand-waving symphony for her own voice, conducted by her own hands. To be fair, she doesn't do it all the time. I notice it at work, where I sit next to her in our little gray cubicles, tethered to a computer by a headset designed by someone with no concept of "head" or "set" and how they should fit together. Lil' Sis perches on the edge of her chair, elbows on the desk, hands moving back and forth like a Tai Chi master. It is as if she moves the air in front of her, it will somehow push her words into the microphone and find that small, reasonable part of the caller's brain that everyone (supposedly) has. The more difficult the caller, the more hand-speech is involved. At times, when her mouth isn't moving, Lil' Sis' hands will alight on the keyboard to type in information. Occasionally, her right hand will click the mouse while her left hand independently churns the air.
I have long since believed that if she had no hands, she would lose half of her vocabulary.
Her hands have quite a way to get the point across.
Take today for instance; While driving home, I saw a yellow Volkswagon Bug. In compliance with all car games, I immediately pinched Lil' Sis twice with a "Tweet! Tweet!" to signify that I saw the yellow car first, and then repeatedly hit her on the knee while chirping, "Buggy car! Guess what color?"
Without hesitation or any warning, she whipped around and slugged me in the arm.
"Yellow!" she shouted.
I immediately stopped hitting her knee. It wasn't very hard, as my arm went numb from the shoulder down. It was a perfect knuckle shot to the shoulder - I could practically hear my muscle scream in protest.
"Ow! Ouch! Owie!" I shouted.
"Oh, I'm sorry!" Lil' Sis exclaimed, immediately contrite. "You can hit me back if you want!"
Tempting as it was, I declined the offer. "No, thanks. There's no sense in both of us being in pain," I gritted out.
That's what I said, but what I meant was, "No, thanks. I don't think there is any possible way for me to hit you quite as hard as you have hit me."
Maybe next time, I should let my hands do the talking.