When you misplace everything. Nothing is out of the question. There is nothing too big, too small, expensive or rare that you cannot lose. It's like a less exciting version of where's waldo, except you're looking for your iPhone X, your Tesla, or your $16 bottle of Rosé. If its mitchaking you crazy, don't worry, you're not alone.
To absolutely disrespect a girl that you are with just so you can get with another girl. No matter what, whether you are hooking up, going out, or even married, you still will take advantage of any situation in which you can get ass.
Steve was hooking up with Mary but then he made out with Amy at a party. Steve just mitched Mary