As you know I’m not that knowledgeable when it comes to bikes.
Anyway some dude at my work has one of these attached to his bike I for the life of me I cannot suss out what it’s for.
I never seem to see the owner of the bike so never get to ask, so I figured I’d ask the pros.
Anyone?
Also apologies for the size, the pic was way bigger when I uploaded it.
Wee Ride kiddie seat mount.
potato 
And the mystery is solved.
Cheers.
I have seen those around and figured it was some weird stupidly heavy lock thing that people never bothered to use because it was so weird, and so they just left on their bikes.
I went through that whole mental process of thinking (1) “what the hell is that?” (2) “oh, it’s a weird lock thing” (3) “man, those people are stupid with their weird lock things”.
Reminds me of the time I took a bouldering mat to the outdoor cinema to sit on, and I could hear some people behind me saying: (1) “hey, what is that weird mattress”, (2) “looks like some weird seat thing for picnics”, (3) “man, how stupid, it’s so big and cumbersome, just buy a rug dude”.
We all do it in our ignorance.