Fun things to do with your dog?

I have a chihuahua terrier mix and i really want to do something fun with him. He doesn't swim,fetch,or play with toys besides his little teddy bear. It's REALLY hot in arizona in the summer so i can't take him for walks or hiking or any of that stuff. Also i don't want any answers on teaching him new tricks (that gets really boring) or obstacle courses (my little brother will just tear it up). We are going to take him to the dog park tomorrow in the late evening but that's it. I would take him for walks in the evening but my parents won't let me go out alone late in the day.