What is 4/20, and why is it a stoner holiday? A look at how ‘420’ became linked to marijuana Friday is April 20, or 4/20. That’s the numerical code for marijuana’s high holiday, a homage to pot’s enduring appeal and universal slang for smoking. Festivities are planned worldwide, culminating with a synchronized smoke at 4:20 p.m. How the marijuana-loving world came to mark the occasion is believed traceable to five Northern California men now in their 60s with bad backs and graying hair. They are the unofficial grandmasters by virtue of the code they created nearly 50 years ago as students at a suburban San Francisco high school in 1971. ADVERTISEMENT ‘‘We thought it was a joke then,’’ said David Reddix, a filmmaker and retired CNN cameraman. ‘‘We still do.’’ Get Ground Game in your inbox: Daily updates and analysis on national politics from James Pindell. Enter email address Sign Up Reddix and his four buddies — Steve Capper, Larry Schwartz, Jeff Noel and Mark Gravich — were a

A 20-year-old was shot and killed by a stranger, but his organs wound up saving five other lives. Mario Cousin’ family recently met the people who received his organs, and his mom even got to hear her son’s heart beating inside one of those recipients. Watch their incredible meeting: SEE VIDEO

WHAT HAPPENED: A passenger was killed on a Southwest flight from New York to Dallas when an engine on the plane blew, sending shrapnel into a window. One of the victim’s relatives says she was partially sucked out of the window before passengers pulled her back in. Seven others were injured. Here’s what happened, including video from inside the plane: WATCH SAY WHAT?! A photo from the plane shows nearly all passengers wearing their oxygen masks INCORRECTLY. A flight attendant tweeted the picture, with the message: “PEOPLE: Listen to your flight attendants!… Put down the phone, stop with the selfies… and LISTEN. **Cover your NOSE & MOUTH.” SEE PIC

President Trump’s personal attorney, Michael Cohen, appeared in court in New York yesterday over an FBI seizure of his documents. In a surprising twist, Cohen was forced to reveal the name of one of his clients: Fox News host Sean Hannity. Later on his show, Hannity said he’d sometimes received legal advice from Cohen but never paid him. NY TIMES “That sounds normal. He has a lawyer he doesn’t pay… By the way, I’m thinking of hiring Michael Cohen as my lawyer. He only has three clients and apparently he works for free.” — Jimmy Kimmel

WHAT HAPPENED: The United States, U.K. and France launched more than 100 missiles at three chemical weapons facilities in Syria as retaliation for an apparent chemical attack in Douma that killed dozens of people, including children. The Pentagon says the airstrikes were a success and took out the “heart” of Syria’s chemical weapons program. REUTERS WHAT’S NEXT: Russian President Vladimir Putin warned that more Western attacks on Syria would bring “chaos” to international affairs. Today the U.S. is expected to announce new economic sanctions on companies “dealing with equipment” related to Syria’s alleged chemical weapons use. CNBC

OKLAHOMA: Oklahoma teachers have ended a nearly two-week walkout that shut down schools throughout the state. The announcement comes on the heels of a vote on tax hikes set to bring in $450 million for education– amounting to a roughly $6,000 raise over three years. REUTERS AROUND THE COUNTRY: Teachers in Kentucky are set for a “day of action” to protest a new bill that revamped teacher pension benefits. In recent weeks, teacher strikes have closed schools in West Virginia and Oklahoma, and teachers in Arizona are also getting ready to walk out. COURIER JOURNAL

ALL OPTIONS ON TABLE: The U.S. says “all options are on the table” in response to a suspected chemical weapons attack in Syria, but that a final decision on military strikes hasn’t been made. The White House says Russia and Syria are responsible for the alleged chemical attack, in which dozens of people were killed. BBC TWITTER THREAT: President Trump warned Russia, via tweet, about missiles that will be headed to Syria: “Get ready Russia, because they will be coming, nice and new and “smart!” You shouldn’t be partners with a Gas Killing Animal who kills his people and enjoys it!” The tweet followed comments from a Russian official who said Russia would shoot down incoming U.S. missiles. THE HILL

For the second year in a row, Austin, Texas has been named the best place to live in the United States. Colorado Springs came in second, followed by Denver, Des Moines and Fayetteville, AR

President Trump said he’ll decide in the next 24 to 48 hours whether to retaliate militarily against Syria for the alleged chemical attack on civilians this weekend. Trump told reporters: “We cannot allow atrocities like that. Cannot allow it… If it’s Russia, if it’s Syria, if it’s Iran, if it’s all of them together, we’ll figure it out and we’ll know the answers quite soon.”

CHEMICAL ATTACK: The United Nations Security Council will hold an emergency meeting to discuss a suspected chemical attack by the Syrian government on civilians. The attack happened in the Syrian city of Douma, killing dozens of people, including entire families. NPR RESPONSE: In a tweet, President Trump blamed Syrian President Bashar Assad and his allies, Russia and Iran, for the attack, saying “President Putin, Russia and Iran are responsible for backing Animal Assad. Big price…to pay.” BBC MISSILE STRIKE: After President Trump’s warning, there was an airstrike at a Syrian base– although the Pentagon denies responsibility. Syrian state media initially said the attack was “American aggression.” Russia is blaming Israel for the missiles.