To plead the Fifth refers to the 5th Amendment of the US Constitution, which gives everyone in the US the right to a fair trial and the right to remain silent. In popular speech, people often say they'll plead the Fifth if they don't want to comment on something, even if it's not a legal matter.

Dog is a word that entered the English language around the 16th century. Its meaning has never changed. Before that, English used the word hound. Strangely, this word is not related to any other. No one knows where the word came from. You might as well ask a dog. They like it when you talk to them.

Grawlix is the word for symbols used in cartoons to show swearing, like "!!#&*!". Grawlixes first appeared in a 1901 cartoon, but the term dates from 1980, created by cartoonist Mort Walker. Walker's book The Lexicon of Comicana is a tongue-in-cheek taxonomy of comic strip drawing conventions.

Goon means "hired thug" and entered the language in the 1930s. The Goons are a race of strong hominids that Popeye encounters in his Thimble Theater comic strip. Alice the Goon is hired by the evil Sea Hag, but Goons are not fundamentally evil. Anyway, the word originated in Thimble Theater.

Alcohol is of Arabic origin. It originally meant a powder that comes from distilling liquids, and referred to makeup. Today it refers to intoxicating spirits, which can also help make someone look better.

AD stands for Anno Domini, Latin for "Year of our Lord". AD 1 is the first year, since that's the year Jesus is said to have been born. (No known birth certificate exists.) CE stands for Common Era. This is more considerate and accessible because everyone who uses this system is not a Christian.

The word "rice" came to English from French--and to French from Spanish--and to Spanish from Arabic. We never changed couscous around, though.

The word jungle entered the English language via Hindi, first recorded in 1776. The Hindi word jangal refers to arid places with little vegetation and few trees. By 1849 the word could also include places of lush, overgrown vegetation. The original definition is rare these days.

The Napoleon Complex is attributed to short men who are aggressive, presumably to compensate for their height. In fact its namesake, Napoleon Buonaparte, was 5'7" (163 cm) tall--about average for a man of his time. The height myth was the creation of British cartoonists. It did get under his skin.

"Are we having fun yet?" is a quip written by Bill Griffith, creator of the Zippy the Pinhead comic strip. It suggests cultural fatigue, when someone is telling you you should be having fun, but you just can't tell. Griffith made the mistake of never trademarking this line. Otherwise he'd be loaded.

Cat language by Kliban.