“You don’t have to be crazy to work here, but it helps” is a jocular sign that has been placed in many workplaces. “You don’t have to be crazy to work here…but it helps” has been cited in print since a least 1941, when it was said to be an old saying about Hollywood. In 1942, the saying was used in the petroleum industry. In 1943, the saying was applied to the federal government in Washington, DC.
 
“You don’t have to be crazy to work here—we can train you” has been cited in print since at least 1996.
 
 
27 September 1941, Seattle (WA) Times, “Queen Anne Graduate Climbing in Hollywood” by Bob Hughes, pg. 16, col. 1:
HOLLYWOOD—There’s an old saying about Hollywood that goes: “You don’t have to be crazy to work here…but it helps.” I’m still looking for that guy who says you don’t have to be.
 
Google News Archive
20 September 1942, Youngstown (OH) Vindicator, pg. B2, col. 5:
A sign of the swiftness of the pace with which the hurly-burly of change is sweeping the petroleum industry, is given by a printed card that now hangs behind the desk of the research director of one of America’s greatest oil companies. The card read: You don’t have to be crazy to work here, but it surely helps!
 
28 June 1943, Evening Times (Cumberland, MD), “Time For Plain Talk” by Bill Cunningham, pg. 7, col. 2:
Boston, June 28—The Washington bureaucracy came in for a bitter pasting from Senator Brewster of Maine in an exclusive interview he granted your correspondent.
(...)
“A commonly accepted saying in the burgeoning bureaus in Washington is, ‘You don’t have to be crazy to work here, but it helps.’ Many of the people can’t see any sense in what they’re trying to do, but they go on doing it just the same because there’s nobody in authority who can tell them to change.”
 
Google Books
The Philadelphia Murder Story
By Leslie Ford
New York, NY: Dell
1945
Pg. 219:
“There’s a sign over in the promotion department that says ‘You don’t have to be crazy to work here, but it helps.’ I suggested they move it over here.”
 
Google Books
Trucks, Trouble, and Triumph:
The Norwalk Truck Line Company
By Wayne G. Broehl
New York, NY: Prentice-Hall
1954
Pg. 89:
Perhaps the sign on the wall of the Cleveland office has an element of truth to it— “You don’t have to be crazy to work here, but it helps!”
 
Google Books
Styles of Political Action in America
By Robert Paul Wolff
New York, NY: Random House
1972
Pg. 200:
On his secretary’s desk was a sign that read, “You don’t have to be crazy to work here, but it helps.”
 
Google News Archive
24 October 1983, The Register-Guard (Eugene, OR), pg. 8B, col. 1 classified ad:
You don’t have to be crazy to work here but it helps.
   
Google Books
Don’t Get Mad, Get Funny!:
A light-hearted approach to stress management
By Leigh Anne Jasheway-Bryant
Duluth, MN: Pfeifer-Hamilton
1996
Pg. ?:
Post-it notes (“You don’t have to be crazy to work here ... we can train you.”) ...
 
Concord (NH) Monitor
January 4, 2008
Photo by Ken Williams / Monitor staff
Connecticut Sen. Joe Lieberman, an independent, campaigns for Arizona Sen. John McCain, a Republican, at the Brown Bag Deli in Concord yesterday. He held a sign saying, “You don’t have to be crazy to work here. We train you.”
 
21 March 2009, Detroit (MI) Free Press, “Secondhand Shop, First-Rate Idea” by Jeff Seidel, pg. C1:
Overall, they have a simple philosophy, which is proclaimed on a sign in the back room: “You don’t have to be crazy to work here, we’ll train you.”