Oh, Baby! is a unique, more worn and rusty version of the super sledge. It is slightly more powerful than the standard variant and has a moderately quicker rate of attack. It also has noticeably larger striking surfaces. It is one of the strongest melee weapons in the game, despite its condition when first picked up.
It's special V.A.T.S. attack is "Mauler", which does 50% damage at the cost of 43 action points and has a chance to knock enemies down (requires a Meleeskill of 50). Outside of V.A.T.S. it can be activated by running and holding down the attack button.