A salty phrase with roots in Ancient Rome has confounded English speakers for centuries. Join Slate Plus! Members get bonus segments, exclusive member-only podcasts, and more. Sign up for a free trial today at www.slate.com/podcastsplus. Twitter: @lexiconvalleyFacebook: facebook.com/LexiconValleyEmail: lexiconvalley@slate.com

Learn more about your ad choices. Visit megaphone.fm/adchoices