[Ghost Rider]

I've got a co-worker that needs me to give his car a jump start. I've got the cables and I know the battery is in the trunk. I also know there is a positive post in the engine compartment to hook the positive cable to. My question is, where do I hook the negative cable clamp? Do I just hook onto the fender or what? I haven't had to give anyone a jump in 15+ years.