buzzing noise?

so i let my friend take my car around the block, lets just say i shouldnt have trusted him. and now between 3500-4000 rpm, theres a vibrating/buzzing noise....anyone know what this could be...the sound more or less goes away after about 10 minutes of driving, but im still pissed..and you can hear it at the higher rpms (6k+) sometimes

Is it an engine buzzing, or like a is somthing like loose?

engine buzzing

so..anyone know?

Maybe you need your valves adjusted? is it a buzzing or a clicking?

definately a buzzing

It seems like it would be a vibration.. maybe you have a bees nest under your hood?... J/K

yeah its a vibration sort of thing but it buzzes, maybe its just a loose bolt or some crap, i dunno im gunna get it checked out