avoirdupois-man, n. — Green’s Dictionary of Slang

avoirdupois-man n.

also avoirdupois-pincher

[SE avoirdupois, the standard system of weights used in the UK before metrication; it covered all goods except precious metals, precious stones and medicines]

a thief of brass weights from shop counters; his profession was known as the avoirdupois lay.

1703		Hell Upon Earth 4: Some are Ingenious at the Avoirdupois-Lay; which is, going into a Shop under the pretence of buying some small scription [...] and by clapping a Glove, Handkerchief, or Sleeve over Brass Weights, convey them away.
c.1786, 1796		Grose Classical Dict. of the Vulgar Tongue (ms additions, 3rd edn) n.p.: Avoirdupois Lay. Stealing brass weights off the counters of shops. Cant.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1846		Swell’s Night Guide 108/2: Avoirdupois-pincher, generally signifies a juvenile petty thief or prig who steals the weights from shops and then sells them to the fence coves.