A dog crack can either be a dog's butthole, or a human's deformed butthole.
A dog crack usually happens at birth and causes poop to be lumpy, small in size, and sometimes causes worms since
the person has a dog crack.
The person cannot perform anal sex because her/his butthole is too small for the job. They can only do it in the front.
The person's dog crack can attract other dogs. If a dog sniffs or tries to hump the person's butthole, or
anything else a dog does to another's butthole, then that is
perfectly normal.