When you ruin somebody's day by telling them some really bad news or make them do something really horrible, usually the receiving person is in a very good mood before said action happened.
person 1: I just won a scratch off ticket.
person 2: Your dog just got hit by a car.
person 1: Man, you just shit in my cherrios!
person 2: Your dog just got hit by a car.
person 1: Man, you just shit in my cherrios!
by ldfkuyg93585uvdofijgh566 January 4, 2009
Get the shit in my cherrios mug.(true story) when you are about 8 years old and enjoying a bowl of some honey nut cheerios in front of the TV and your older brother casually walks up to you half turns lifts his leg and farts your direction and a little diarhea accidently falls into your bowl of cheerios.
by -Blackbiurd August 29, 2017
Get the Shit in my cheerios mug.