Suddenly coming to one's senses by forgoing a contemplated course of action you might later regret.
We were on our way to buy more liquor when I had a smart attack, turned the car around, and called it a night.
That heart-stopping moment when you realize that as a teacher, or a firefighter or a small business owner...or any other hard-working middle class American...that voting Republican is voting against your own best interests.
Joanne: You are NOT going to believe this! Fireman Tom is voting for President Obama!
Robert: Are you kidding me? That die-hard Republican? He must have had a MAJOR smart attack!
Joanne: I know, and it's for real. He didn't even call the paramedics...