One of the many downsides to the Autistic mind, at least to your brother.

Motormouth and Monkey are out jumping on the trampoline.
Motormouth: You can't see me.
Monkey: Yes I can.
Motormouth: You can't see me. I'm invisible.
Monkey: You're right there.
Motormouth: No, I'm invisible, you can't see me.
Monkey: Yes I can.
Motormouth: You can't get me because you can't see me. I'm invisible.
Motormouth: OW! HEY! You can't see me!
Monkey: I got you.
Motormouth: Hey! You. Can't. See. Me!!!
Monkey: I got you.
Motormouth: Stop. Stop. Ow. Stop.
Monkey: hee hee.

Ah, pretend play. Maybe someday.