The nickname was originally coined and used in the 1990s and early 2000s.
Nerfer (Noun) - A person who is passionate about Nerf blasters and play.
John loves Nerf. He and his team of Nerfers play at the park every Sunday.
Typically, the term Nerfer is a unisex nickname; the nickname can be used for both male or female fans of Nerf. In recent years, however, with Hasbro's expansion on the female-oriented Nerf Rebelle line, certain terms for female Nerfers have come to light such as Nerfettes. These terms are not widely used.
Just as the term "Nerf gun", or "Nerf blaster", has become a blanket term for foam blasters, in recent times, the term Nerfer has become a blanket term for one who enjoys playing with foam blasters. It may refer to anyone who falls under the category from all brands, no longer simply just Nerf. This could possibly be due to the acceptance of other brands in the Nerfing community.