To massage the third limb, usually only practiced on a male although can be practiced on a female under special circumstances.
Synonyms for squeaking the duck are but not limited to:
Wanking
Buffing the Banana
Choking the chicken
Used to imply masturbation, in a polite form.
Doug was totally Squeaking the Duck last night in the spare bedroom! Surprised you guys didn't hear it!
Mom walked in on me Squeaking the Duck last night, Lucky i was able to quack it away in time.