4/20 is least known for being Adolf Hitler's birthday, or the day of the Columbine High School shooting.
Most instantly get the thought of "pot," "weed," or "marijuana" when those numbers are mentioned.
Blaze Pizza is offering a special for their app users:
Burger King brings a 10-piece spicy chicken nugget just for $1.69!
Freebirds World Burrito - giving out a marijuana free "pot brownie" with the purchase of a Monster Burrito all day on 4/20.
Hopdoddy Burger Bar: the special "High Roller" burger features a taco-seasoned beef patty topped with pepperoni & mozzarella, Flamin’ Hot Cheeto ketchup and cool ranch fries all in between two hemp seed buns. (And on the side, a spoonful of cookie dough, of course.)