Look Who's Talking (1989)
Single mom Mollie (Kirstie Alley) is looking for love, and overlooking Mr. Right, a kindly cab driver named James, played by John Travolta. If only she could hear what her infant son, Mikey, is thinking about her choice of men -- though she'd probably be disturbed to know that he's thinking in the voice of Bruce Willis, and he's full of snarky comments and wise-beyond-his-months insights. This movie spawned a couple of sequels, so if one sarcastic baby isn't enough for you, check out Look Who's Talking Too, in which Roseanne Barr provides the voice of Mikey's new sister, Julie, and sibling rivalry flares.