The non-dominant hand (my left hand) is an "A" or an "S" handshape.
(You'll see it either way).
The dominant hand is a bent hand and is held so that the fingers are
underneath the pinkie side of the non-dominant "fist." The dominant hand
"unbends" and bends one time as if showing gas escaping.
FART (version 1)
Here is a "one handed" version of fart. (Both versions are widely used.)
You start by opening up the pinkie, and then the ring and middle
finger. The index finger stays curled up. Then you reverse and close
the middle, then ring, then pinkie fingers. For comic effect or
emphasis you can puff one cheek and force a bit of air through your
lips at the corner of your mouth.
FART (version 2)
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Language (ASL) online at American Sign Language University ™
by Lifeprint.com © Dr. William Vicars