A very common way to sign "corn" is to use your index finger to
represent an "ear of corn."
Hold it near your mouth and twist it forward twice. (You don't have
to make any chewing movements or anything, just twist it like I'm
showing you.)
Also see:
BUTTER
Also see: SALT
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American Sign Language (ASL) online at American Sign Language University ™
ASL resources by Lifeprint.com © Dr. William Vicars