Patty Simcox is a character in the 1978 movie, Grease.
She is a cheesy do-good cheerleader, beautiful and highly intelligent, though to Rizzo, she's the "bad seed of Rydell High". She was played by Susan Buckner in the movie, by Elle McLemore in the 2016 live performance, and by Lauren Haine (alongside her co-star and singer, Matthew Lloyd whom played Haine's love interest) in the 2017 play version.
Kenickie also pranked her many times in the film, such as hiding a rat in her school bag in the middle of a lesson.
At the National Dance-Off, which she had organized, Patty came in wearing a blue strapless dress, blue high heels, a blue hair piece and blue gloves, basically all blue, but nothing really went well for her. She was laughed at from the start, she got covered in tissue paper when a prop fell on her, when she finally got her chance to actually compete in the dance off, she ran out in the middle of the whole school (and live television cameras) and jumped and danced.Kenickie then ran up behind her and lifted her dress above her head, exposing her matching blue underpants, he forced her to dance around in a circle with her dress over her head, making sure the whole school saw her, before letting it go. She then ran off crying while everyone cheered and laughed. She was then seen again at the dance when Danny and ChaCha won the competition, she is again teased for her humiliation. After the dance, her exposed underpants are seemingly forgotten, as she sees Rizzo at school, and teases her by telling a group of her friends 'she's the one I was telling you about'.
In the final scene, she is shown to be with Tom Chisum.