Lucy T. Slut is a vixenish but really cute night club singer from the Tony-award winning musical, Avenue Q. She was originally performed by Stephanie D'Abruzzo; now Carey Anderson performs her in the American version while Julie Atherton performs her in the UK version, while voice actress Melissa Fahn played her at another time. There are several different puppets of Lucy used in the show, all built by Rick Lyon. She is a singer at the Around the Clock Café, a fictional local eatery and bar in New York City.
In act two of Avenue Q, Kate Monster stops by Princeton's apartment to give him a note to meet her at the top of the Empire State Building to attempt to patch things up between them. He is in the shower, so she leaves the letter which is destroyed by Lucy. When Kate Monster is waiting on the top of the Empire State Building for Princeton (the note was the invitation) she gets frustrated and throws Princeton's lucky penny (a gift to her from him) off the side of the building, hitting Lucy in the head. Once Lucy recovered, she became a born-again Christian ("That penny knocked out 20% of my brain, but it only knocked out the mean stuff!"). It should be of note that Lucy's heart monitor readout is curiously but hilariously in the shape of the curvature of large breasts.
The character is likely named after Lucy Westenra, a character from the Dracula mythos who is also seductive and vivacious, and is visually based off of Jessica Rabbit, a character from Who Framed Roger Rabbit?. She might also be reminiscent of Marilyn Monroe and Anna Nicole Smith.