This article is from the Scientology and Dianetics FAQ, by email@example.com (Scientology Information Server) with numerous contributions by others.
According to "The Basic Dictionary of Dianetics and Scientology," the
term "squirrel" is defined as follows:
SQUIRREL. 1. a squirrel is doing something entirely different.
He doesn't understand any of the principles so he makes up a
bunch of them to fulfill his ignorance and voices them off on
a pc (pc = pre-Clear, an individual on the road to going Clear;
see the book _Dianetics_ or the Scientology Catechism for a
description of "Clear") and gets no place. 2. Those who engage
in actions altering Scientology, and offbeat practices. -v. to
change and invent processes.
Thus a squirrel group would be a group of people doing the above. Once a
person has received auditing from such a person, it can be difficult to
get standard auditing in a Scientology organization. For instance, there
is now a special auditing action which people who have been in "est" may
receive (at the direction of the Case Supervisor, the person who prepares
the auditing programs), to resolve any incomplete actions or case
difficulties brought about by participation in this group.