There was a move about 4 or 5 friends who accidentally kill a stranger-turned out to be a cop.
In the process, they go to a wedding, and have to hide the body in their car during the wedding. There is a girl who is wealthy living off savings or a trust fund.

They end up killing an old woman who may have seen them dragging the body out of their house. All the friends end up turning on each other, and I think they end up burning down their apartment at the end...

Can't remember exactly, but something close to that. Can anyone give me any help??

Very Bad Things.

I meant to add more to that, but I hit enter... anyway, it sounds like Very Bad Things, but I don't know.