Owning giant pickup trucks and SUVs. I'm not that secretive about it, though. I assume everyone driving them is an insecure, overgrown child who wants a big vroom vroom.
I'm not sure about everyone else, but in my case you assume correctly. The only reason I'd want a monster truck is to act like an overgrown child who wants to show off his big vroom vroom. Also, with a mandatory funny honk.