Ya, I remember doing that... exactly once! I was in grade 4. Hated arithmetic, and had a test that day. When I got to school, I told the teacher that I wasn't feeling well. I was directed to the school nurse, who took my temp, called my mom, and sent me home.
Little known to me at the time (but never to be forgotten), the nurse was a friend of my RN mom. They decided to teach me a lesson. When I got home, mom was waiting for me. She told me to go straight to bed, and that the school nurse was coming over on her lunch break to see how I was doing.
Well, a few minutes before noon, mom came in and told me I had to have an enema, and that the nurse was going to help. When she got to our house, I heard them talking, then they were in the bathroom running water. Shortly after, they both came in and while mom was hanging the bag, the nurse was putting a towel under my bum. Try to imagine two nurses giving a 9 year old a bag enema. Mom had the lube, and the nurse had the nozzle. Before I knew it, the enema was flowing and they were talking while I was squirming.
Soon enough, the enema was over. I never forgot that day, and I never tried to BS my mom again. I did get sick from time to time, but I never faked it again. I also got enemas from time to time, but never like that again!