pain smile
A fake grin that looks like it was carved out of your face with a rusty spoon, usually when you're trying to hide how much something hurts or how bad you messed up.
My boss asked me if I wanted to try the new coffee. I said yes. It tasted like burnt socks and regret.
I tripped in front of my crush and smiled like I was proud of myself. I wasn’t.
When my dog ate my homework, I gave a pain smile that screamed 'this is not going to end well.'