Not every idiom comes from a single grand event. Plenty are just old slang that stuck around, rooted in ordinary spoken English rather than a documented incident.
29 idioms in this category
"The whole thing; everything, with nothing left out."
Likely Origin (Disputed)"There you go; it's as simple as that."
Still a Mystery"Engaged in petty cheating, fraud, or dishonest dealing, especially for small personal gain."
Likely Origin (Disputed)"To mock, tease, or make fun of someone, often gently."
Still a Mystery"Ordinary, basic, without any special features."
Well Documented"To put in more effort or power, especially when driving or exerting physical force."
Well Documented"Not very intelligent, or not quite right in the head."
Well Documented"To have a chat, especially a long or gossipy one."
Still a Mystery"To be extremely frightened or nervous."
Still a Mystery"To be very expensive."
Well Documented"To pursue a mistaken assumption or the wrong course of action entirely."
Well Documented"To get straight to the point, skipping unnecessary detail."
Well Documented"To carry a grudge or a persistent, defensive resentment, as if spoiling for a fight."
Likely Origin (Disputed)"Extremely pleased or delighted."
Likely Origin (Disputed)"The genuine, authentic thing, not an imitation."
Well Documented"A near success that still falls short of actually winning or succeeding."
Well Documented"To take on more responsibility or work than you can actually handle."
Likely Origin (Disputed)"To leave, or set off on a journey."
Likely Origin (Disputed)"Said or done without preparation; improvised on the spot."
Well Documented"To shift blame or responsibility onto someone else."
Well Documented"A deliberately blank, unreadable expression that gives nothing away."
Likely Origin (Disputed)"A playful, softened way of telling someone to stop prying into your business."
Likely Origin (Disputed)"In a powerless position, forced to do whatever someone else wants."
Well Documented"To cost far more than is affordable, or (in gambling) to win more than the house can pay out."
Well Documented"In a risky or precarious situation where one wrong move could cause things to go badly."
Well Documented"To become involved in a stubborn conflict or confrontation with someone."
Well Documented"Abstaining from alcohol."
Well Documented"In a risky, exposed position, especially by taking a stance others haven't supported."
Well Documented"To enrich or benefit yourself, usually through dishonest or self-serving means."