Blonde moment

Let me first say that last night was my girls night, so I got home late. Plus my 3 boys were up at
6 a.m. so I got very little sleep. I also woke up with the worst headache in the world, it lasted all day long.
Okay, I'll get to the point. I had to go order my bridesmaid dress for my brothers wedding today. I try the dress on, it's a size to big so the sales clerk says she needs to take my measurements over my clothes. I thought that was odd, why would I put my dress on over my clothes. So I get dressed and put the dress on over my jeans and tee shirt. She comes in the dressing room and says" I actually need to do the measurements over your clothes". I say oh, ok and pull the dress down a bit so she can measure the top, then she says again, I need to measure over your clothes. Then it hits me,mind you it's been a good 5 minutes, I started laughing and tell her I get it now. I shouldn't even have the dress on. She laughs and says no, no you shouldn't. The rest of the time, I'm shaking my head tying not to feel like the dumbest person on the planet. I keep telling her I'm usually not that dense, I'm really not myself today. She was super nice about it, she said it made her day. She needed a good laugh.
Really not my proudest moment.