A non-existent item that veterans tell apprentices or new hires to fetch from the stores. It is a classic hazing ritual designed to make the newcomer look foolish when they ask the storeman for it. The joke relies on the impossibility of a liquid paint drying in a plaid pattern.
Heard on the job
Go down to the tool crib and ask Gary for a tin of tartan paint and a left-handed screwdriver.
Insider tip
If someone asks you to fetch this, a bucket of steam, or a glass hammer, they are testing your common sense.