I agree with eco, my ASD son is hilarious. He was reading Captain Underpants at 4, and appropriately using the humor from it. (I will never forget him walking into the kitchen and saying, "Hey, Mom, what's 50 feet long and smells like pee?")
If you want to rule it out once and for all, get an evaluation from a respected autism expert. If he says it's not autism, make sure that his teachers know he has been evaluated and the expert says it's not autism. Our health insurance covered this with nothing but an office visit copay.
