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."