Dressing up or down?

[Big Man]

... we're invited to a bar opening Saturday night being put on by a friend in country music management. The invitation calls for "concert casual" dress. Sounds like that means an old concert t shirt, jeans, and tennis shoes will be fine, right? ...

I've enjoyed reading all the comments in this thread. But I'm curious. What did you wear? And , almost more importantly, what did the others in attendance wear? What was the apparent definition (in the context of this event) "concert casual"?