When TV characters hold a birthday party or baby shower or a similar event, the party will be attended by four or five familiar characters, as well as about twenty people who have never been seen before and will never be seen again. Since we see pretty much every aspect of the characters' lives, we can't help but wonder who these people are and when the characters had time to befriend them. Strangely, by the time of the relevant character's next birthday, they've completely changed around their extraneous circle of friends. Also, rarely will the main characters ever interact with these people at the party, unless it's just for a quick throwaway joke, so one must wonder why all these extras are even at this party to begin with.
This is especially common in sitcoms.
Not to be confused with the movie 24 Hour Party People, a biopic of Factory Records and the Manchester music scene in the 1980s/1990s, though both the trope and that movie are named after the Happy Mondays song.
See also New Neighbours as the Plot Demands and Social Circle Filler.
In the infamous "So bad it's good film" The Room, the latter part takes place at a birthday party Lisa throws for Johnny. The party is full of people that the audience has never seen before but the kicker is the character of Steven who has never been introduced up until that point and somehow is involved enough in the plot to give counsel to the main characters. (The character was actually supposed to be another character that was introduced previously, but that actor and the infamous Tommy Wiseau got into an argument, resulting in Wiseau firing him and replacing him with the other actor, hoping no one would notice.)
This is the case with Reed Richards's bachelor party, in Fantastic Four: Rise of the Silver Surfer. Justified since Johnny arranged everything.
Reed: Johnny, I don't know who these people are!
Johnny: Oh yeah, I was going to invite your friends, but you don't have any.
Friends is particularly guilty of this. We saw a lot of the six main cast members, and they pretty much exclusively hung out with each other and possibly whoever they were dating at the time. Virtually every party they held was attended by a very large cast of unknowns.
Lampshaded when Rachel and Phoebe throw a engagement shower for Monica and invite everyone in her address book who could make it on 24 hours notice. Phoebe's response: "Who the hell are all these people?"
Gunther usually was at their parties as well. Lampshaded when one of them is planning a party and says they have to invite Gunther since they've been talking about it loudly in the coffee shop.
Used by Reese in Malcolm in the Middle episode "Lois's Sister." Other episodes explain that Reese just invites random people to any party since he has no friends, being a Jerkass.
Happens on How I Met Your Mother when Ted's 30th birthday party on the rooftop has dozens of guests. Also hilariouslylampshaded in the first season when Ted throws a 3-day party just for the sake of hooking up with Robin again. Barney explains that, at any sufficiently large party, there will be someone there who you don't know and who doesn't know anybody you do know. To wit:
Barney: Hi, have you met Ted?
Random Girl: No.
Barney: Do you know Marshall? Lily?
Random Girl: No.
Barney: Hmm. Do you know anyone at this party?
Random Girl: I work with Carlos.
Barney: Excuse me.
(to Ted, Marshall and Lily)
Barney: Anybody know a Carlos?
(they shake their heads)
And the lampshading and the hilarity continues when they meet at the following party:
Random Girl: (behind Barney) Hello, Barney.
Barney: Of course...
Random Girl: You look well. Isn't it weird they invited both of us?
Barney: Who? Who invited you, no one even knows who you are!
Random Girl: I understand, you're hurt, but... you don't have to be cruel. Carlos was right about you.
Also subverted for Lily's bridal shower. Robin is invited and expects to spend the evening with all of Lily's friends, only to find that she's the only friend there - the rest are family.
Lampshaded in Queer as Folk's first season, when Michael has a birthday party attended, apart from his close friends, by dozens of strangers. Brian explains that in order to have any kind of crowd he had to open up the invite list to his own past sex partners.
This happens a number of times in House, although in this case, it's more or less justified; it's a hospital drama, and therefore the show is 90% set in a work environment.
In one episode, Cuddy has a christening for her adopted drug addict baby, Cameron, Chase and Wilson show up. Along with about 20 randoms no one has seen before.
Chase's bachelor party was also attended by people nobody had seen before and never saw again.
Justified on Roseanne. When the family throws a party celebrating having won the lottery, it gets increasingly bigger to the point that Dan has no idea who he was just talking to. Obviously, the partygoers were strangers trying to be friendly to get a piece of the money.
Occurs on Amen. Thelma is having her wedding shower at her house. The Hettabrink sisters and Inga are there, but then there are about 15 other women, supposedly Thelma's friends and fellow church members, that we have never seen before and never will again.
Happens in Monk whenever the whole police department is gathered, remarkably at Monk's surprise birthday party.
Subverted in the Buffy episode "Dead Man's Party." The point of the episode was to have a big party, with a bunch of people at it that Buffy didn't know (the original intent was to have a welcome back dinner with her friends and mother, which would have averted this trope entirely, but where's the drama in that?). The same thing happens again in "Older and Far Away", only in the more traditional sense (and with Dawn as the focus).
Happened at Scully's baby shower on The X-Files, though since Scully has no female friends other than one seen in season one and she looks visibly awkward, it's plausible that they're a mix of co-workers and women her mother knows.
Played with on an episode of General Hospital. Carly's mother organizes a bridal shower for her. Although the women present are known to the viewers, they are virtual strangers to the bride-to-be, who has no friends thanks to her nasty personality. Adding insult to injury, they've brought gifts not for her, but for her infant son.
Sex and the City may have been just as guilty of this as Friends. Anytime the girls hosted a birthday party, baby shower, wedding etc.; most of their guests were a bunch of random characters that were never seen before and would never be seen again for the rest of the series. Keep in mind that when these girls went out to parties, only the four of them attended together about 90% of the time. Their dates were there for the following 10%. Just how good were these friends they kept inviting?
Done a few times on Charmed. First with Piper's baby shower and later would be done for every birthday party Piper's children had. You could probably also count Prue's funeral and the funeral Piper, Phoebe, and Paige had when they faked their deaths.
Played with in an episode of The Fresh Prince of Bel-Air. Will's friend Jazz is getting married with Phil performing the ceremony. Will comments on the number of guests who showed up and Phil says "Are you kidding? I hired these people. Jazz ain't got no friends!"
Justified in an episode of The Drew Carey Show: Drew plans to invite a few people from work over to his house to drink up the last of his homebrew beer. Mimi pranks him by putting his flyer in the weekly Winfred-Louder newspaper stuffer, so he ends up with practically all of Cleveland in his house - including Special Guest Stars Joe Walsh, Little Richard, and Cleveland's then-mayor. note Also seen in the background is Grant Shoud, who would later play a character who dates Kate and claims he's the devil. Presumably it's the same character even though he never does anything in the party episode. Conversely, Walsh later plays a guitarist in Drew's band who is most definitely not Joe Walsh.
Lightly averted on Freaks and Geeks. In the "Beers And Weirs" episode's house party, most of the people attending aren't directly friends with Lindsey, but we can assume enough word got around about it that several non-Freak/geek classmates decided to attend (anything for some free beer!). Also, there are quite a few side characters at the party (such as Mark, who would later be revealed as Nick's pot dealer).
A glaring example occurred in the second season of Angel. Three main characters are happy about some money coming in to Angel Investigations. Two of them have recently been exiled from their respective social circles and the other has little to no social life due to her Cursed with Awesome visions, yet somehow they throw a party at the office where 24 Hour Party People are seen dancing and then never seen again.
A couple off the party-goers do show on at least one other occasion as Cordelia's friends and it was implied that she had amore active social life in the beginning of the series.
In Breaking Bad, Jesse once threw a massive party. He didn't care how much money he spent, who was there, what happened at it, how bad his house was trashed, so long as it never ended. As a result, we justifiably don't know many of the guests.
Frasier: Every time Frasier or Niles hold a party, plenty of people show up who the audience has never seen before, seemingly just to fill party space. These people often leave offended; one wonders how they keep meeting these folks! On the other hand, their social circle is frequently described as being composed of interchangeable, shallow, insincere socialites who will turn up to whatever gathering will make them look good.
A notable exception is The Simpsons, which has so many characters now that any gathering will consist entirely of people who were featured in at least one past episode (although it may be completely ludicrous for them to attend the gathering in question). In fact, The Simpsons has random extras instead of Faceless Masses. It's not that unusual for an animated show to have its party people to be the same at every party. After all, you only need to draw these characters, and they don't necessarily have to have any lines. In a regular, non-animated sitcom, you would either have to hire the same group of extras for every party, or only use crew members and friends of crew members as background talent.
Parodied in the episode How I Wet Your Mother, when Homer throws an apology party after angering all his coworkers. At the table with Lenny and Carl, a female extra notes this is the best apology party Homer has ever thrown. Lenny, still smiling, casually asks "Who the hell are you?"
Lampshade Hanging occurs in the Rocko's Modern Life episode "The Big Answer." Two random background characters show up as guests at Filburt's bachelor party. When Filburt asks who they are, Rocko realizes he doesn't know either.
In the Beetlejuice cartoon, the Neitherworld literally sells these. In cans. Needless to say, when Beetlejuice buys some, it does not end well.
The extras on My Little Pony: Friendship Is Magic turn into this whenever a party happens, though most of those parties are organized by Pinkie Pie, who claims to know everyone in town and probably does. If anything, the birthday party she throws for her pet alligator stands out for having such a small guest list. Less justified is Diamond Tiara's cuteceaņera, where we clearly see a few adults arriving not accompanied by a minor, including Twilight Sparkle, one of the show's mane characters.
In Care Bears episode "Care Bear Town Parade", everyone is in the parade, so who is in the audience? The parade-watchers are extra bears who exist only in this one episode. They all look like clones of Tenderheart in different colors, though this is not obvious unless one pauses the video.