Ryan was looking forward to sleeping over at his friend Robert's house. Though they had been classmates for a while, the two had only recently become good friends. Ryan packed up his sleeping bag, a pillow, and a few of his favorite toys and games, and then his mom dropped him off at Robert's. Robert met Ryan on the porch and the two did their secret handshake and started playing right away. First they played pirates in Robert's tree fort. Next they played ninjas in the driveway. Then it started getting dark and they went inside of Robert's house. As soon as they walked in the house, Ryan's eyes starting getting red and itchy. He saw a big orange cat sitting on the couch. Then he started sneezing uncontrollably. "I'm sorry, Robert. It's been a lot of fun, but I have to call my mom." Why does Ryan want to call his mother?