Ascended Meme: The Rebirth is Cancelled joke that Northernlion and his friends started can be one of the messages that you get from fortune tellers. A bit ironic, since NL discredited the meme because Fan Dumb who couldn't read the sarcasm started giving the devs shit over it.
Creator Backlash: Edmund is reportedly furious by how quickly the Lost was discovered.
The reason Edmund was furious was because the Lost was discovered via Datamining, when he intended it to be a "community project" to try and find it.
Fan Nickname: As the game doesn't give you the names of normal enemies until the credits, players tend to give them these. Anyone who has watched Northernlion enough tends to use "human popcorn", "silkworms", "Conga Line" and "zambies", in place of their real names (Mulligan/Host, Butt Licker, Charger/Spitter, Knight).
Meatboy Lvl. 5—That's what some players call the severed body "generated" by The Shears. The reason behind it is because it used to be possible to have it constantly following you by acquiring five Meat Cubes via glitch exploitation.note It's still possible to acquire more than 4 Meat Cubes, but now the fifth one you get transforms into a new rotating Meat Cube instead of upgrading your 4th Lvl. Meatboy.
An even more common one is "Blue Baby" for the unwieldy ???. For the True Final Boss as well as the character. This was ascended as of one of the updates, with his will being signed as "???? (a.k.a. The Blue Baby)"
Pooters are known as "Grandfather Flies" because their white abdomens look like beards.
One of Us: Possibly, since one of the Challenge names in Rebirth is Glass Cannon, which starts the player off with the Book of Belial, Loki's Horns and Epic Fetus.
Promoted Fanboy: Spider, the mind behind the SpiderMod program (a modified version of Isaac that runs in a separate .exe, is more optimized, and adds a number of features including various cheats and controller support) was hired to do coding work for the remake.
Sleeper Hit: Word of God has stated he never expected Isaac to be so popular. At one point he considered giving it away because he didn't believe anyone would actually want to spend money on something so weird and dark.