Activities for three year olds

My mom was asked to watch my three year old cousin over night next week and I was wondering if you had any fun activities for children that age. I want to have fun and have things to do so he doesn't get bored or miss his parents. Any ideas? I was thinking about making cookie dough and buying a monster truck (he loves monster trucks) cut out and then letting him decorate cookies. Is that suitable for his age? Also I looked on pinterest and didn't really see anything that looked like something he'd enjoy doing. Thanks!