Her fiancé Rob Kardashian made that mistake and it did not end well.
In a sneak peek for Sunday's upcoming episode of "Rob & Chyna," the 29-year-old drives while Blac Chyna raids a bag of fast food in the passenger's seat. When Rob's french fries fall on the floor, Rob has some not so well-received advice for his future wife.
"You gotta choose one, the food or your phone, either or," the 29-year-old tells Chyna. "Either or, what's more important?"
Chyna reacts by giving Rob a death stare before launching into a tirade against him for blaming her for the french fry spill.
"These are my fries, those was your fries," she says.
Not picking up on the fact that the mother-to-be is in no way interested cleaning up the mess, Rob presses on asking, "You're not gonna help out?"
"Didn't you just see I'm about to go down?" Chyna yells. "I didn't see that s--t falling, God! You gotta relax."
But she doesn't end her rant there.
"This is your stuff," she points out. "You should've been holding it."
Rob, who points out that he hasn't raised his voice during the entire exchange then lightly calls out Chyna on her rage.
"Yo, you have serious anger issues," he says, while laughing.
When his comment prompts her to start ripping into him yet again, he says, "Why are you yelling, you psycho?"
Watch the entire fast food feud in the clip (above)!