The Eternal BOB (often abbreviated as TEB) is bob's ultimate true form and serves as a major boss fight in Slap Battles, added on June 23, 2023. To trigger the fight, four players must coordinate with specific gloves: a Killstreak user, a Reaper user, a Tycoon user, and a bob glove user. The Killstreak and Reaper users each need at least 3 kills, and all four must be near a bob entity. The God's Hand player then activates a time stop, transporting everyone into The Dark Realm. The Eternal BOB is an enormous, multi-phase boss with shockwave attacks, falling meteors, and sweeping hand slams — requiring strong teamwork to defeat. It is one of the most epic events in all of Roblox Slap Battles and a rite of passage for serious players.

In Slap Battles, the name "bob" is an acronym for Bringer of Blindness — a title confirmed by the game's creator, Tencelll. According to game lore, bob was originally Erebus, the ancient Greek god of Darkness. He was a mischievous and destructive deity who tormented mortals until the other gods sealed him inside a Gauntlet as punishment. They stripped him of his fearsome name and reduced it to the humiliating nickname "bob." The humans were then able to wield the Gauntlet and summon his trapped form — but unknowingly, every time they use bob's power and every soul he absorbs, bob grows stronger, slowly working toward his eventual true form: The Eternal BOB. This rich mythology is a big reason why the Slap Battles community is so passionate about bob as a character.

The bob glove in Roblox Slap Battles is considered one of the most coveted gloves in the game. To obtain it, players first need the Replica glove, which requires accumulating over 4,500 slaps. When using the Replica glove's ability, there is a 1 in 7,500 chance (approximately 0.013%) that the clone it spawns will corrupt and transform into bob. When this occurs, the player earns the bob badge, which unlocks the bob glove. Another player must be present in the arena for bob to spawn, as bob needs a target. Due to this extremely low probability, many players grind in private servers with friends or alternate accounts to maximize their chances. The bob glove allows players to summon a bob entity that relentlessly chases the nearest opponent.

Defeating bob in Slap Battles is notoriously difficult, which adds to his terrifying reputation. In his standard in-game form, bob can only be eliminated by the Cube of Death — a special object on the map. Players who are being chased can look for the Cube of Death and strategically lure bob toward it. When bob collides with the Cube of Death, he lets out a loud scream and disappears. Additionally, turning into a rock (via certain gloves or abilities) will also cause bob to die upon contact. Players can also simply leave the platform boundaries to eliminate him as a target, though the chase will restart with another nearby player. Understanding how to survive a bob encounter is considered essential knowledge in the Roblox Slap Battles community.

In Slap Battles lore, bob and rob are considered counterparts — often described as opposing forces or evil and good equivalents within the game's mythology. Rob is another major lore character in Slap Battles, and the two share a deeply intertwined story. Most notably, rob plays a significant role in the lead-up to The Eternal BOB boss fight — when a bob entity collides with a rob entity in the arena, special events are triggered, and during the boss fight's later phases, rob's voice can be heard guiding players. The community has long debated and theorized about the full nature of the bob versus rob dynamic, making it one of the richest ongoing lore discussions in the Roblox Slap Battles fanbase. Both characters have inspired their own beloved plush toys, with the bob plush being among the most sought-after by the community.