In an alternate dimension, the sands of time flow backwards.
An alien with a human face and a human with an alien face sit down at a cafe.
The human-alien hybrid orders a black hole smoothie and the alien-human hybrid orders a cosmic latte.
"So," says the human-alien, "Have you heard about the planet that imploded and then exploded?"
The alien-human nods, sipping his cosmic latte. "Yeah, they say it was all because of a missing sock in a parallel universe."
The human-alien chuckles. "Isn't it strange how the punchline of this joke is actually the beginning?"
The alien-human grins. "It's like an anti-joke, but in reverse."
They both laugh, but as time rewinds, their laughter turns into silence.
The human-alien ponders, "What do you think the punchline was?"
"Well," says the alien-human, "I think the punchline was that the missing sock caused the planet's demise. It's not funny when you think about it, but it's the absurdity that makes it amusing."
The human-alien nods, "It's like an anti-joke inception."
And with that, the joke un-tells itself, leaving them in a state of blissful confusion.