At the beginning of the reign of Simon the Postman, Shirley Magnifico was a 15 year old resident of Festeron, living with both her father and older sister Gloria in a small cottage on River Road. Her mother had not been around for years, she had ran off with a portable-toilet salesman. Shirley was a good-looking girl with a full head of blonde curls.

During the curse of Witchville, Shirley commonly dressed in promiscuous attire--high-heeled boots, jeans so fittly snug that they gave the appearance that they had been sprayed on her rear, and a tight sweaters. She tended to lighten and curl her head, although on her it looked cheap, not anywhere near as sophisticated as the look her more beautiful sister easily achieved. In fact, Gloria's attractiveness provoked bitter jealously in her heart.

Shirley dated Brad MacGuffin for an indeterminate period prior to Simon's arrival at Festeron, when he set up a crooked shell game at the Fun Pier. Simon made it easy for Shirley to find the pebble beneath the three cups, only to lure Brad into betting a gold coin. He fell for the scam. But when Shirley’s older sister, Gloria arrived, Simon was mesmerized by her beauty. Wanting to impress her with his generosity, he formed a fašade by returning the coin to Brad, and lied that it had accidentally fallen out of the cup. The couple only dated for one more day, for after that, Brad MacGuffin was devoured by Amy Sue Grue.