non illegitimi carborundum

A humorous pseudo-Latin expression meant to translate as "don't let the bastards grind you down," meaning do not succumb to the oppressive influence of others. "Carborundum" is another name for silicon carbide, the synthetic form of which has been used as an abrasive since the late 19th century. You've got to have thick skin and nerves of steel to make it in this industry. Just remember—non illegitimi carborundum! The protestors stood outside Capitol Hill, many with signs reading, "Non Illegitimi Carborundum."