If games count then all the radio stations in GTA

The lore books in The Elder Scrolls series, hands-down.

There is an entire universe of conflicting knowledge, personal bias, and unreliable narrators that leave Tamriel's history feeling very real, and very open to interpretation. The fun of it is piecing together the truth somewhere in the middle. But I'll die on the hill that the Arcturian Heresy is absolute horseshit written by a madman, and comparable to the scribbles of a paranoid schizophrenic on an anti-vax forum. Anyone who references that volume in regards to Tiber Septim and the forming of the empire is an impressionable dweeb.

McBain in The Simpsons is a classic.

This video stitches the movie together somewhat.

https://youtu.be/BzjfrdcN1Z8?si=G84IdUwMkfPKDm3w

Springtime for Hitler, The Producers https://youtu.be/1zY1orxW8Aw

I'm a big fan of fake brands/products in anime. I don't know why, but they bring me joy.

"Ow, My Balls" is a claaaassic.

Crash Nebula and The Crimson Chin from Fairly Oddparents are both great

Interdimensional TV on Rick and Morty

Fillory and Further by Christopher Plover

within

The Magicians by Lev Grossman

Fillory in the magicians trilogy by Lev Grossman is fantastic.

Surprised that no one has mentioned Vegemorphs from PBS's Arthur yet.

Camp Pining Hearts from Steven Universe. Does Fiona and Cake from Adventure Time count?

As The Stomach Turns. It was a classic parody of soap operas on The Carol Burnett show, and as someone from that era i can vouch that it was a pretty spot on parody, at least from what i saw on tv when staying home sick from school.

Galaxy Quest the Show inside Galaxy Quest the Movie

Do the Justice Friends from Dexter's Lab count?

There's so much in Infinite Jest, but I think my favourite would be "Blood Sister: One Tough Nun".

The lusty argonian maid

The Princess Bride is one of my favorite examples of this, especially because the "story within the story" is the main story, which is unusual.

I'm surprised no one has mentioned the fake old movie that plays in Home Alone. "I'm gonna give you till the count of 10 to get your ugly yeller no good keester off my property before I pump your guts full of lead! One... Two... Ten!" 🔫🔫🔫🔫🔫

Tales of the Black Freighter from the Watchmen comics is pretty awesome.

All My Circuits on Futurama is one of my favorites on tv. Dramatic beeping intensifies.

Ow! My balls! from Idiocracy

There's been some stuff coming out lately that makes me think this show isn't far off.

Angels With Filthy Souls

The "adult" movie Kevin watches in Home Alone. Apparently the main dude who was supposed to be in those didn't show up so they just had some janitor or tech fill in and he went full ham on that shit and made it something to remember.

There's also the McBane movie in The Simpsons that shows up in multiple episodes and if you connected them all together they actually make a coherent story line (it's just riffing off Lethal Weapon anyway).