It happens to a lot of new mums - the difference being that most of them don't have their lives documented on TV.
Kim, 33, laughed the whole thing off but her sister Khloe, 29, and brother Rob, 26, were less than impressed about the...er...leakage.
Kim was wearing a light grey top during a conversation in her mother's kitchen with her siblings, when she began lactating.
Khloe was the first to notice, telling Kim: "Your boob is, like, leaking out of control."
As they looked at the large mark on Kim's T shirt, Khloe continued: "It is like a water fountain!"
Her brother Rob, however, was slightly freaked out by the whole thing.
He said: "What the f*** - that weirds me out, for real. That just weirded me out."
So much so, that he had to leave the room. Oops.
He should try being in the UK and watching Luisa and Lee 'lactating' in the Celebrity Big Brother house - that whole incident has left us emotionally scarred.
Kim has been breastfeeding her first baby, North West, since her arrival in June.
In fact, it's been reported that Kim is so committed to the breastfeeding cause, that she planned ahead for her recent trip to Paris, leaving North in the care of her mother and sisters - armed with Kim's breast milk.
She pumped extra breast milk ahead of the trip and then froze a supply for North.
Kim's mother Kris, as well as a team of nannies, were then on standby to feed North her usual supply of milk while Kim was away.
Kim, who got engaged to Kanye West, 36, in October recently revealed that she loves any small bonding moments she gets with her baby.
She admitted that despite it sounding 'crazy,' she even enjoys changing North's nappies.
She explained: "I love that time. I know it sounds crazy, but I love my time with her when she's on the changing table. She tries to talk so much and I really enjoy that bonding time when I'm with her."