As a customer, how would you have handled this?

[Shengirl]

he stops gets out of the car, pulls down his pants and starts flipping his genitals around in front of her.

I would have revved my engine to see how fast he could get back in his car.

[Andara Bledin]

You've got his license plate. Report the bugger for littering!

I'd do it in a heartbeat.

It's a huge fine and the guy would know it was from you, with love.

^-.-^

[crazylegs]

One of the delightful powers i have in my job is the ability to fine people for littering , so take Regristration number (licence plate) run the details then pay them a visit with a £50 ($100) fine.

[Becks]

Would that make your car a ... litterbug?

Beat me to it!!

he stops gets out of the car, pulls down his pants and starts flipping his genitals around in front of her.

I might have reacted as per the quote below:

I would have revved my engine to see how fast he could get back in his car.

Or pointed and laughed at him. For a long time. I can do that.

[Jester]

Flipping the bird might provoke something worse, as people have noted, but a good death glare can do wonders. Amazing how often such a wordless gesture will cause people to reverse their actions or not do what they were about to do.

I would have reported it to the litter hotline
http://www.azdot.gov/highways/adoptahwy/HotLine.asp

I feel the need to point out that that litter hotline is for my home state of Arizona only, so unless you live in the Grand Canyon State, that particular hotline won't do you much good.

Hopefully your own state/province/municipality has their own litter hotline as well.