One of the oldest and most popular of lawyer jokes is:
 
What ‘s black and brown and looks good on a lawyer?
A doberman.
 
The joke has been cited in print since at least 1986 and has been included in many collections of lawyer jokes. It’s not known who first told the joke.
 
   
Google News Archive
8 October 1986, The Courier (Prescott, AZ), “Three candidates agree on Proposition 103” (UPI), pg. 5B, col. 6:
“What is brown and black and looks good on a lawyer?” he asked. “A Doberman pinscher.”
(Fromer congressman and state senator Sam Steiger.—ed.)
 
Google Books
Skid Marks:
Common Jokes About Lawyers
By Michael Rafferty
Bolinas, CA: Shelter Publications
1988
Pg. 12:
What ‘s black and brown and looks good on a lawyer?
A doberman.
 
22 September 1988, The Post-Standard (Syracuse, NY), “An Abundance of Litigation, An Overabundance of Laywers” by Lynn Bartels (Scripps Howard News Service), pg. D-4, col. 3:
Do you know what’s black, brown and tan and looks good on a lawyer? A Doberman.
 
Google Books
Partners
By John S. Martel
New York, NY: Bantam Books
1989, ©1988
Pg. 102:
“Do you know what’s black and brown and looks good on a lawyer?”
“What?” said, Rachel, still smiling.
“A Doberman pinscher.”
 
Google Books
Lawyers and Other Reptiles
By Jess M. Brallier
Chicago, IL: Contemporary Books
1992
Pg. 57:
Question: What’s black and brown and looks good on a lawyer?
Answer: A doberman.
 
Google Books
American Folklore:
An Encyclopedia
Edited by Jan Harold Brunvand
New York, NY: Garland Pub.
1996
Pg. 908:
What’s black and brown and looks good on a lawyer?” (Answer: a rottweiler [Variant: a doberman]).
 
Google Books
The Lawyer’s Joke Book:
There Are Some Things a Rat Just Won’t Do
By John Patrick Dolan and Dale Irvin
Advantage Media Group
2008
Pg. 30:
What is black and brown and looks good on a lawyer?
A Doberman.