I'm sure you've seen this, if not experienced it.
You're sitting in the drive through at McDonald's, waiting for your order to be filled. In the parking lot, a group of young "adults" exits a car. They begin to offer conversation to their buddy, working inside at the drive through window. Statements such as, "Flip those burgers!", "Hey, can I get free food?!", and the like all are offered up as topics of conversation.
Normally, a good employee at such a place will shrug it off and let the cronies walk past. Other times, though, the employee will respond, and join in with the juvenile torments.
Something similar happened to me today at work. A former employee was utilizing the services of the car wash. He tried to start a conversation with me, when he was about 50 feet away from where I was, and even though I had a customer in the shop who I was tending to.
I was the responsible employee and just ignored it.