The Rumor: New Yorkers are rude.

The Truth: Fuhgeddaboudit! “It’s absolutely false that New Yorkers are unfriendly — they may seem standoffish at first, but that’s just concealing a very big heart,” insists Ed Koch, a former mayor and a quintessential New Yorker. (Hey, someone who appeared in The Muppets Take Manhattan should know.) So what is with the gruff exterior, then? Call it a coping mechanism for living in a city of more than 8 million people. “We believe that people want their own space, so we don’t intrude unless asked for assistance. But if you’re visiting from out of town, just walk over to any New Yorker and he’ll immediately help you out,” says Koch. And rather than feeling upset about a brusque cab driver or a bagel guy who seems to toss your change at you, remember that they are just trying to keep the wheels in motion. “People here want to help you get on with your day!” says Koch.

The Rumor: Afternoon thunderstorms in Florida always pass within an hour.

The Truth: “This does not always happen, but a lot of storms are pretty quick,” says meteorologist Nicole Mitchell. “In the heat of the afternoon, there is enough of a contrast between the slightly cooler ocean air temperature and the warmer air temperature over land to trigger storms,” she says. “By late afternoon, there is less of a contrast and you lose the trigger for the storms, so they start dying out.” And Florida is not the only place you should keep an umbrella handy. Mitchell says the same conditions exist up and down the Gulf Coast, making the weather in places such as Biloxi, Mississippi; Mobile, Alabama; and New Orleans equally erratic.

The Rumor: South of the equator, toilet water swirls in the opposite direction.

The Truth: This one goes straight down the commode. Wondering where that crackpot theory originated? “South of the equator, tornadoes go clockwise, while north of the equator, they go counterclockwise, because of the earth’s rotation and something called Coriolis force. In principle, the same would happen to water in a toilet or a bath,” explains Michael Goodchild, a professor of geography at the University of California, Santa Barbara, and a 2007 recipient of the field’s highest honor, the Prix Vautrin Lud. “But the effect of Coriolis force on a small scale is very weak and outweighed by other forces, like the relative positions of the inlet faucet and the plug hole.”