According to the Bellingham Heraldthe slogan was created in 1995 by Stephen Stimson   a Bellingham native and the former owner of Lone Wolf Antiques.  Back in 1995, his mother suggested that he paint a “Welcome to Bellingham” sign on the north outside wall of the Lone Wolf building next to Whatcom Museum. He credits inspiration for the phrase to Gary Stephenson, a high school artist friend. He appreciated Stephenson’s low-key approach to art and humor.  The slogan has certaqinly taken root, it is in the Wikipedia description of Bellingham and a BBC travel entry on the city.