Maybe you can explain?

I was unlocking the front doors at one minute before official opening time today. I like to do that, give people that little "extra." Anyway, there were the usual type of MUST GET ON THE INTERNET RIGHT NOW people there, who invariably shove past as soon as the door opens a crack and who dash in to get their Information Mainline fix. There was a guy who would go right for the Classifieds in his neverending search for employment. And there was this other guy I had never seen. He was not young, but he was dressed in clothes I typically associate with the young. As the of six doors was unlocked and I beckoned the assembled in, he said, "Very nice, you get a cookie."

Others laughed like this was a good joke, but I'm not sure what he meant. Maybe it was just I was a dog who performed a trick? But that doesn't seem enough for such merriment. So is there some cultural reference I'm missing? I don't watch a lot of TV, so generations of catchphrases sail right by me. Help? Anybody? Beuler? <--there an elderly pop culture reference proving that I am current up to about 1986.