To tell a lie or tall story. Originates from Rush Green in Romford, Essex. Shifty is a well known exaggerator from that area, and the term "Shifty's mouth" or " to Shifty" has also been heard as far as Ramsgate in Kent, England.
He told me he was at the pictures last night, "Shifty's mouth", he was with me all last night.
by Couch Potato April 10, 2015
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