ASL Linguistics:  metathesis
Also see "linguistics"

Metathesis:  When parts of a sign change places.  For example: The sign Deaf is often signed by touching your cheek or jaw near your ear then touching your cheek near your mouth:

DEAF:

 

...can also be signed starting at the cheek near the mouth and moving to the jaw near the ear:

Both versions are correct.  (But some people don't know that and will tell you you are wrong  correct you and tell you are wrong.)

Some other signs that can and sometimes do exhibit metathesis include flower, parents, home, member, contacts, etc..  It seems like almost all of the signs that use both the left and right side of the chin can start on either side:  cafe, restaurant, senior citizen, bachelor, twins, Arizona...(etc.)

Not all signs can do this though.  Actually, most signs CAN'T use metathesis.  For example, "improve."  If you sign "improve" using metathesis, you will actually change the meaning of the sign to "deteriorate."