line your pocket

   wrongfully to enrich yourself

   The money provides the lining:

    ... adept in the field of corruption and lining his own pocket. (Goebbels, 1945, in translation)

   In America, as line your vest:

    I think he's been lining his vest. (R. Moss, 1987 — he was not a tailor but an official suspected of peculation)

   An obsolete form was line your coat, although Shakespeare's observation of human behaviour is, as ever, timeless:

    And throwing but shows of service on their lords,

   Do well thrive by them, and when they have lin'd their coats,

   Do themselves homage. (Othello)