question???

[Laura]

I have a question but im not sure how to ask....I was looking under the back tail end of the truck and i noticed this clearish/whitish handle looking thing that sorta plugs in the rear end...whats it for and what is its name, it looks like you could pull it out and your hand looks like it could fit purfect right threw it...dont laugh at my discription, i just didnt now how elese to discribe it and its another one of those qusetion i want to have a quick answer for when im asked or maybe i shouldnt even care (but i do)