Can't Stop the Music

Songwriter Jack Morell (Steve Guttenberg)-a reference to Village People creator Jacques Morali-gets a break DJing at local disco Saddle Tramps. His roommate Sam Simpson (Valerie Perrine), a supermodel newly retired at the peak of her success, sees the response to a song he wrote for her ("Samantha") and agrees to use her connections to get him a record deal. Her connection, ex-boyfriend Steve Waits (Paul Sand), president of Marrakech Records (a reference to Village People record label Casablanca Records), is more interested in getting back with her than in Jack's music (and more interested in taking business calls than in wooing Samantha), but agrees to listen to a demo.
Sam decides Jack's vocals won't do, and recruits neighbor and Saddle Tramps waiter/go-go boy Felipe Rose (the Indian), fellow model David "Scar" Hodo (the construction worker, who daydreams of stardom in the solo number "I Love You to Death"), and finds Randy Jones (the cowboy) on the streets of Greenwich Village, offering dinner in return for their participation. Meanwhile, Sam's former agent Sydney Channing (Tammy Grimes) orders Girl Friday Lulu Brecht (Marilyn Sokol) to attend, hoping to lure the star back. Ron White (Bruce Jenner[a]), a lawyer from St. Louis, is mugged by an elderly woman on his way to deliver a cake Sam's sister sent, and shows up on edge. Brecht gets Jack high, which unnerves him when her friend Alicia Edwards brings singing cop Ray Simpson, but Jack records the quartet on "Magic Night". Ron, pawed all night by the man-hungry Brecht, is overwhelmed by the culture shock of it all and walks out.
The next day, Sam runs into Ron, who apologizes, proffers the excuse that he's a Gemini, and follows her home. Spilling leftover lasagna on himself, Sam and Jack help him off with his trousers before Jack leaves and Sam and Ron spend the night. Newly interested in helping, Ron offers his Wall Street office to hold auditions. There, Glenn M. Hughes, the leatherman climbs atop a piano for a rendition of "Danny Boy", and he and Alex Briley, the G.I. join up. Now a sextet, they get their name from an offhand remark by Ron's socialite mother Norma. Ron's boss, Richard Montgomery (Russell Nype), overwhelmed by the carnival atmosphere, insists the firm not represent the group, and Ron quits.
Ron's new idea for rehearsal space is the YMCA (the ensuing production number "YMCA" features its athletic denizens in various states of undressâalong with The Simpsons Movie, the film is one of the few non R-rated offerings to feature full-frontal male nudity). The group cut a demo ("Liberation") for Marrakech, but Steve sees limited appeal and Sam refuses his paltry contract. Reluctant to use her savings, they decide to self-finance by throwing a pay-party.
To bankroll the party, Sam acquiesces to Channing's plea to return for a TV ad campaign for milk, on the condition the Village People are featured. The lavish number "Milkshake" begins as Sam pours milk for six little boys in the archetypal costumes with the promise they'll grow up to be the Village People. The advertisers want nothing to do with such a concept, and refuse to air the spot. Norma then steps in to invite the group to debut at her charity fundraiser in San Francisco. Sam lures Steve by promising a romantic weekend but Ron is taken aback by the inference that she'd go through with the seduction, and Sam breaks up with him. On his private jet, Steve prepares for a tryst, but it's Jack and his former chorine mother Helen (June Havoc) who show up, to hash out a contract. Initially reluctant, Helen seduces Steve with her kreplach and before long they're negotiating the T-shirt merchandising for the Japanese market.
In the dressing room before the show, Ron, relieved to learn Sam didn't travel with Steve, proposes to her. At one point, Montgomery shows up to rehire Ron as a junior partner representing the group. Following a set by The Ritchie Family ("Give Me a Break"), the Village People make a triumphant debut ("Can't Stop the Music").

Question: What musical number is playing in the TV ad?
Answer: "Milkshake"