Shirley "the Loon" McLoon, a female waterfowl, is a citizen of Acme Acres featured in Tiny Toon Adventures.
Shirley is one of the few characters of the show not directly inspired by an existing Looney Tunes character, but she bears more than a passing resemblance to Melissa Duck. Although she seems reasonably intelligent, she speaks with a thick Valley girl accent and is obsessed with superficial New Age paraphernalia. Her name is derived from fellow New Age aficionado Shirley MacLaine, while the latter part of the name is an obvious pun. More often than not, characters refer to Shirley as "Shirley the Loon" rather than "Shirley McLoon." She appears not to notice the negative connotations of the nickname, and, in fact, the mantra she recites while meditating is "Oh, what a loon I am. Oh, I'm a loon." Shirley is often pursued romantically by Plucky Duck and Fowlmouth. When not meditating or fortune-telling, Shirley hangs out with her Acme Looniversity classmates Babs Bunny and Fifi La Fume. She also appears to be a skilled sorceress, as in one episode, she used her powers to give Plucky the IQ of Einstein to help him ace a test.
In "Love Disconnection", while attending a high school dance, Shirley gets doused with red punch (driving her into a tranquil fury as seen in the movie Carrie), then proceeds to flood the gym with her telekinetic powers.
Shirley is a keen ballerina who has to face prejudice when attending an upmarket ballet school otherwise attended exclusively by Perfecto Prep swans. Jealous at her superior dance skills, they mock her accent and try to sabotage her performance at their recital, but are soon thwarted by Shirley's nimble moves and a behind-the-scenes Babs, staging a sabotage of her own.
Shirley did not have an end tag.
Shirley is voiced by Saturday Night Live and Laugh Trax alumna Gail Matthius. Matthius's voice for Shirley the Loon is loosely based on the one she uses for her recurring character, Valley Girl Vicki (who appeared on both SNL and Laugh Trax).