This is not the dumbest thing I've ever said, but there's no way anyone can top Madoff's Met's contribution, so here goes.
When I was 8 or 9, the family took a big trip down to Florida to visit Disney World. We also visited my grandparents, who lived a couple hours away.
One day at the grandparents' house, it was just about lunchtime. My mom asked me to go tell my older brothers and sister to come eat. I dutifully padded back to the enclosed patio and let them know. My sister, who was probably 13 and just entering into the most awful phase of her teenage years, turned to me icily and said "screw you, Eric."
Now as an innocent 8 year old, I didn't know what that meant, but I was pretty sure it was bad, and sure as heckfire I wasn't about to let this opportunity go by without getting her in trouble. So in the absolute loudest, deepest voice I could muster, I yelled back "NO, SCREW YOU, JEN!"
Satisfied, I strolled back to the kitchen for lunch, smug in the knowledge my sister would be in trouble, and was promptly smacked in the mouth by my grandmother.
* names changed to protect me from you internet weirdos