This happened when I was about 8 years old. My parents had removed all the bedsheets and pillow covers and put them in the wash.
I was sitting in my parents room, watching TV. I don't know how I had a marker, but I had a marker with me. I unknowingly started drawing on the mattress. I drew a peace sign, my signature, and a woman holding a baby.
All of the sudden, my sixth sense went off and I realized that my mom would be coming to put the bedsheets on anytime now. I tried wetting the mattress with a little water to see if the marker would come off. But of course, I was drawing with a Sharpie (permanent marker). I suddenly had the "brilliant" idea to put shampoo on the mattress to get the marker off.
I dumped a whole bottle of shampoo onto the mattress and started scrubbing like crazy. It still wouldn't come off. I heard my mom coming up the stairs and I ran into my room. I heard her come into her bedroom and I guess after seeing the foamy mattress, she screamed. I slowly came into her room and whimpered. I told her what happened. She was about to smack me when my dad came in and asked what happened.
My mom summarized the story. My dad's a really calm and chill guy. He started to laugh and told her to relax. My dad went and got a hair dryer and started to the dry the area. My mom kept scrubbing and all she would get is foam. She got so angry.
I remember my dad sitting there with the hair dryer for about an hour until finally, the soap and water dried up. My mom yelled at me and told me to never do it again. We still have the mattress and it brings up a lot of stories of when I was young and "rebellious". We laugh about it till this date.