squirm

Concise Oxford English Dictionary © 2008 Oxford University Press:
squirm/skwɜːm/

▶verb wriggle or twist the body from side to side, especially due to nervousness or discomfort.

■ be embarrassed or ashamed.

▶noun a wriggling movement.

– derivatives
squirmer noun,
squirmy adjective.

– origin C17: symbolic of writhing movement; prob. assoc. with worm.