What would you do?

I would have picked up my pace and vacated the area as quickly as possible. Perhaps the folks with the cars were Breaking Bad wannabees

He would have called Chuck Norris for backup.

Ray

I agree with frugal fan and I would have gotten the hell out of there. I don't believe the brief case was booby trapped, but I believe you interrupted an illegal exchange of some kind. I don't know if they heard you coming and someone failed to pick the case up. I have a feeling if you looked in it or took it, you would have been pursued.

Dont take the case.

I would have looked around to see if Howie Mandel was somewhere saying "Deal, or no deal?"

My first instinct would be some kind of "joke" booby trap. Like open the case and be sprayed with shaving cream while someone in the cars videos for laughs. But it just as easily could be dangerous. Either way I would probably back off and throw rocks at it to see if the guys in the cars did anything.

You should always mention homosexuals whenever possible. It's good luck!