When you are so tired that when you go to shit and you fall asleep on the toilet. This usually happens while using a public restroom.
After we ordered our food at the restaurant, my friend went to take a shit and fell asleep. He is always sleep-shitting every time we come here at 2 am.
A term used to describe a situation where one needs to smile or act happy even though they are in severe pain physically and or mentally. References how dogs (most dogs) facial expression remains the same even when they are in pain. Usually used to describe an unpleasant interaction with authority.
Another variation of this phrase is shaking like a dog shitting razorblades
"The boss was screaming right in her face but she just stood there smiling like a dog shitting razorblades."