yes it's a bouy,
well actually it's a channel marker. it was washed in during Katrina. those things are alot bigger than you'd think (well at least bigger than i thought) about 7' tall
you can see the water about 1/4 of a mile behind it, that is the bay & no boats there...about 3 miles from here is the gulf where it probably came from. now its just stuck it the grass.
i also found the sign to be unsetteling as i walked over to take the pic.