Carl: "Those Germans aren't so bad."
Lenny: "Sure, they made mistakes in the past, but that's why pencils have erasers!" — The Simpsons

You know who made a mistake that couldn't be erased? A man named Joseph Reckendorfer.

In 1862, Reckendorfer spent a cool $100,000 (2.3 million in today's money) to buy a patent from the horrifically-named Hymen Lipman. Reckendorfer then proceeded to sue a company that was supposedly infringing on his right to exclusivity. The Supreme Court ruled against him, saying the patent was invalid. Reckendorfer was left with nothing.

So what patent did Reckendorfer waste his money on? Well, Lipman, a Jamaican-born Jew, came up with the idea of... putting erasers on pencils! Sadly for Reckendorfer, the Supreme Court said that this invention did not create any new functionality. Thankfully for Lipman, he already made his money.

As for those German mistakes? Alas, those are not that easy to erase.

Sorry, Lenny and Carl.