My 6 year old (7 in summer) was diagnosed with asd a year ago, but at the time I also suspected ADHD, which I mentioned to the EP who scoffed at the idea.
According to the EP, children with ADHD are conspiratorial and try to draw others in to their 'clowning' around. When she first observed DS he wasn't at all socially aware, so probably incapable of either. Now I can see his jokey side is coming out and he spends much of his time fooling around to make others laugh.
Along with the ASD, he is impulsive, has zero concentration and spends the entire evening bouncing along the sofa. He runs off, has no sense of danger even to the point where I am considering reins.