Not sure what I'd call this, but it makes a popping noise like it's flappin' around on the interstate when I go 70+ through heavy wind. What should I use to hold this down?

 

Doesn't it have clips? Replace clips, or glue that bitch down

 

ha ha I was just messing with that on my car yesterday...

Pry the whole thing off with a flathead (or just pull up on it since it's already loose). There's 3 white clips underneath that you push onto and slide over to lock in place with the tabs attached to the roof. Then you snap that thing onto the clips by just pushing it down onto them.

 

Yeah, it's just little plastic slide clips. They have them on eBay for cheap if yours are broken