I constantly look through the Friends section of the pause menu in GTA V and notice that on several save files, people have what looks like a fireman's helmet on Michael? But it's not the firefighter outfit (as seen in the Bureau raid), they're wearing it independently (often with the gray suit). None of them have replied when I asked how they got it and I couldn't find anything regarding it on this wiki. Is it just a glitch, or is there legitimately a way to obtain it?
I only ask because I know GTA V is full of secret missions (Children of the Mountain, The Last One, the Epsilon series).