What does it mean when a guy wags his tongue at you?

Today I was picking up food and waiting for my order to be ready. A group of four guys that looked about my age called at me for my attention. When I looked at them, they were all sticking their tongues out and wagging them at me.

I had no idea what it meant, but it was immature, so I turned away. Then an old man, probably older than my grandfather, who was on the other side of me did the same thing.

Were they just trying to get a rise out of me?
What does it mean when a guy wags his tongue at you?
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