Once again, for the unenlightened

Wikipedia tells us that a bobby pin is a type of hairpin. In British English it is known as a "hair grip". It is a small pin or clip, usually of metal, used in coiffure to hold hair in place. Typical bobby pins are plain and unobtrusively colored, but some are elaborately decorated or jeweled. The "bobby pin" came into wide use as the hairstyle known as the "bob cut" or "bobbed hair" took hold. This trend gained popularity in the 1920s, and the bobby pins kept the bobbed hair in place. Bobby pins are inexpensive and tinted to match various hair colors which led to the fashion trend being adopted by 90% of North American women by the end of the decade.

And the Goody Stay Put band speaks for itself.