Audible Chuckle. Since LOL is so often used in instances when the user has not in reality "lauhged out loud", AC can be used as a more truthful alternative.
George: "Man, that was so funny! lol"
John: "Did youreally lol?"
George: "Nah, I didn't. AC"
One who is on the broader autistic spectrum, including but not limited to those with autism, Asperger's, hyperlexia, and pervasive developmental disorder not otherwise specified. This definition is sometimes extended to include those with AD(H)D.
The group was open to all ACs, whether professionally or self diagnosed with anything from classic autism to PDD-NOS.