Hah! My pet neurosis is fixing badly adjusted bike helmets and backpacks. Badly adjusted climbing harnesses freak me out too, but I can usually refrain from groping total strangers around the butt so that their harness will sit better...

But all my sons friends are used to me swooping down on them to fix their bike helmets. They come in with their helmets way back on the back of their heads with loose straps, and go out again race-worthy...