When I push on the gas in my car I get a rattling noise. What is this?

[stephbrown2005]

And is it really bad? I was in a parking garage yesterday and heard it. I've heard it once or twice before but I didn't think much of it.

 

[kelly_f_1999]

could be a few things likey low oil knock maybe or low octane fuel knock would be smart to just stop at any shop and ask them to listen to it