Yep, it for pulling your wanker out in the bathroom when you have to relieve yourself. I never use it though, its much quicker to just pull it down enough so your penis falls out.
On a side note why are we talking about this? biggrin:
i use it when im in no hurry cuz i dont want my ass hanging out all the time, it helps when you have pants with a zipper on so you just pull it thru 2 mouse traps