"Don't let the bastards grind you down": A pseudo-Latin motto of obscure origins, probably the stubborn remains of an elderly joke. Almost certainly not from the following alleged medieval jingle: "Si te dominorum vis/ Facit furibundum,/ Dico "illegitimis Nichil carborundum". If anyone with a firmer grasp of the classics than me wishes to have a go at translating it, please go ahead.

Carborundum is an abrasive substance made from carbon and silicon.

Illegitimi is simply dog-latin for 'bastards'.

I have seen this rendered Nil illegitimi carborundum, which more closely resembles proper latin, but is still flagrantly 20th-century mock-latin.