As much as the Rick and Morty series hates copying work from other animated series, it straight up stole some of the grossest jokes in Futurama history.
Despite Rick's complete disdain for a direct copy of another animated series ("Do It Yourself" is the obvious exception), Rick and Morty completely steals Futurama's grossest jokes.
Rick and Morty has been a meta-series since season 1, with Rick breaking the fourth wall and other characters throughout the series addressing the fact that they appear in TV shows. This has been underlining the Rick and Morty theme that nothing in the universe matters, not even that everyone is just a cartoon character created for fun. However, just because nothing matters doesn't mean Rick and Morty will be a hack for stealing ideas from other adult animated series. In the Season 3 episode titled "The Rickchurian Mortydate", Rick and Morty are so addicted to the video game Minecraft that they travel to the "Minecraft Dimension" only to drop the entire storyline, as South Park has apparently done. Then, in "The Vat of Acid Episode," Rick initially refuses to make Morty a device that could save his position in time, because he's already seen something like it on Futurama. Interestingly, however, these reservations do not appear to Stop the series from doing something Rick hates in one particular Rick and Morty adventure.
In the Oni Press comic Rick and Morty #52, titled "The Mortian" by Kyle Starks and Phil Murphy, Morty crashes on a dangerous world after flying away from a massive Death Star-like space station in an escape pod. Once Morty arrives, he's nearly eaten by a flying beast, chased by a giant reptile, and captured by a primitive alien race. During his captivity, Morty's captors gave him and his cellmates some sort of slime to eat. While Morty thought it tasted good, others connected to him refused to drink it at all - and then it was revealed why: the slime was secreted from a giant, slug-like alien creature from.
Rick and Morty’s ‘Slug Slime’ is Exactly like Futurama’s Slurm
In Futurama season 1 "Fry and the Slurm Factory", Fry and pals learn how their favorite soda, Slurm, is made after visiting a Willy Wonka-esque factory. What they found was a giant alien slug that secretes a slime that it then processes into a Slurm, although the episode makes it clear Characters can swallow slime straight from the slug if they want to (it sounds gross). Side-by-side, it's clear that the "slug" that Morty encounters in Rick and Morty is exactly the same as the one Fry encounters in Futurama. It's odd that Rick and Morty's characters are so blatantly similar to Futurama's, especially given Rick's apparent hatred of plagiarizing someone else's work, if that wasn't a deliberate label or reference - though explanations may Easier than one would think.
Futurama is known to be the king of sci-fi comedy, especially in the realm of adult animation, so this "slug slime" is likely just a reference or nod to the iconic series to show respect. However, despite the reasons behind it, Rick and Morty seems to have completely stolen Futurama's crudest jokes.