Nametag Easter eggs in Minecraft are hidden and often humorous references that players can discover when using nametags on certain mobs or entities within the game. Nametags are items that allow players to name mobs, pets, and other entities, giving them a personalized touch. However, the developers at Mojang, the company behind Minecraft, have added some clever and playful surprises for players who take the time to experiment with nametags.

Here are a few notable examples of nametag Easter eggs in Minecraft:

1. 
   Dinnerbone and Grumm Upside-Down Mobs: When you name a mob "Dinnerbone" or "Grumm" using a nametag and apply it, the mob will flip upside down and appear to walk on the ceiling. This quirky feature was introduced as a fun way to personalize mobs and add a touch of whimsy to the game.
   
2. 
   Jeb's Rainbow Sheep: Naming a sheep "jeb_" (with an underscore at the end) will cause the sheep's wool to cycle through a variety of colors, creating a rainbow effect. This Easter egg is a tribute to Jens "Jeb" Bergensten, one of the lead developers of Minecraft.
   
3. 
   Toast the Rabbit: Renaming a rabbit to "Toast" will turn its appearance into a unique, toasty texture. This Easter egg is a reference to a tweet by Helen Zbihlyj, a member of the Minecraft development team, in which she showed a picture of her pet rabbit named Toast.
   
4. 
   Johnny: In the "Village & Pillage" update, naming a pillager "Johnny" using a nametag will cause it to become hostile toward other illagers and mobs. This Easter egg is a reference to a popular internet meme related to a player named Johnny who fought against illagers.
   
5. 
   Herobrine: Although not an official feature, many players have tried to create an Easter egg involving the mythical character "Herobrine" by naming mobs "Herobrine" with a nametag. Herobrine is a rumored and unconfirmed character said to haunt Minecraft worlds, but Mojang has officially denied his existence.
   

These nametag Easter eggs add a touch of charm and humor to the game, encouraging players to experiment and explore different possibilities. They also showcase Mojang's commitment to engaging with the Minecraft community and incorporating their inside jokes and references into the game itself. Keep in mind that Easter eggs can change with updates, so it's always a good idea to stay up to date with the latest information about Minecraft.