MOTHER PRANKS: Ann Erekson's favorite April Fool's joke works like this: You take a bag of Oreo cookies, open up each cookie, scrape out all the white filling, and replace the filling with toothpaste. Then you offer the cookies to your children.> This is a mother's kind of April Fool's joke: it's sweet, harmless and also fights cavities.

Mothers put pepper in the salt shaker. They tell their children to call Winder Dairy and ask for Mike Howe. They put food coloring in the milk. These are the kind of practical jokes that let children know that life does not have to be taken seriously.

When Erekson's children were living at home, April 1 always meant salt in the sugar bowl, and cold cereal for breakfast. You run through a lot of cereal that way, she admits, but it was always worth it.

"I have an empty nest now, so April Fool's Day is not half as much fun," says Erekson, who lives in Bountiful. "But maybe I could try something on my Cub Scouts."

ADVANCED PRANKS: Marsha Taggart is also a mother, which means that on April Fool's Day she sends her children to school with slices of cardboard in their sandwiches. But Taggart has also graduated to more elaborate practical jokes. As a more advanced prankster, Taggart does not find it necessary to wait until April Fool's Day to have fun.

Last fall, for example, she and her cohorts, John Olsen and Jim Jesperson, decided to play a little prank on their friends, Carolyn and Craig Benson. While the Bensons (who are BYU fans) were out of town, Taggart and her buddies (who are Ute fans) painted the floor of the Bensons' garage red.

Because she is actually a nice person, Taggart says she wishes she could do that prank over and use water-based paint. The Bensons have discovered that if they want to get rid of the red, they'll have to sandblast.

Taggart, who has developed something of a reputation as a practical joker, got her just deserts earlier this week from her co-workers at Travelers Insurance, where she is a medical consultant.

Her colleagues sent her an electronic message directing her to fly to Atlanta for a chiropractors convention next week. Taggart had arranged for her mother to stay with her children and was calling up to make a plane reservation when her supervisor said "April Fool!"

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DEEJAY PRANKS: In the hierarchy of practical jokers, radio deejays and Dick Clark sit at the top. Their jokes are not only elaborate but have what we all wish we had for our pranks: a big audience.

In the Salt Lake area, the masters are KISN deejays Scott Fisher and Todd Collard, who like to do a thing they call "Candid Calls." Set up usually by a spouse or co-worker of the intended victim, Fisher and Todd (as they are known to listeners) execute these practical jokes on the air.

A few months ago, for example, posing as salesmen for a local boat company, the deejays called Lar-raine West and told her they would be delivering her new boat later that day. With the color-matching trailer and customized details, they told West, the boat would cost $12,000. She should have the check ready when they arrived, they said.

West was stunned that her husband had bought this boat without consulting her. In fact she thought they had been saving the money to buy a new house. The deejays strung her along for several minutes before letting her in on the joke.

Collard says that he and Fisher try to stick to fairly harmless pranks. Their criteria are that "No one gets hurt, everyone has fun and we don't get arrested."

Pranks for the memories

"You'd be surprised how many adults buy this stuff," says Dee Pollard, gesturing to the whoopee cushions and booby-trapped gum that line the walls of his store. Pollard, owner of Showplace Novelty and Magic in Crossroads Plaza, is a purveyor of prank-enhancers such as the following list of April Fool's favorites:

-Trick sweets, including candy that tastes like fish, gum that tastes like garlic, and saltwater taffy with extra salt.

-Booby-trapped items, including sticks of gum that bang when you touch them, cigarettes that bang when you light them, and a dollar bill that can be snatched away when someone reaches to pick it up off the floor.

-Automobile tricks, including a sticker that makes a windshield look broken, and a whistle that can be inserted into an unsuspecting person's exhaust pipe.

-The two biggest sellers, says Pollard, are still the hand-buzzer and the whoopee cushion.