That's an involuntary TWINKLE.
The Big Bang Theory Season 5, Episode 21
Hey, Ma, TWINKLE, TWINKLE,
your little star is home!
The Big Bang Theory Season 6, Episode 4
Hey, Ma, TWINKLE, TWINKLE,
your little star is home!
The Big Bang Theory Season 6, Episode 4
I see that TWINKLE in your eye
The Big Bang Theory Season 5, Episode 21
there it is,
there's that TWINKLE.
The Big Bang Theory Season 5, Episode 21