OK...here's an ernest attempt at a serious answer, still delivered with a smile on my face (from picturing that guy with the 'dance' comment').
Some stuff--understanding, wisdom, discernment--comes with experience...experience with the Word of God and experience given by the Grace of God from the life we've led under His Sovereignty. That includes EVERYTHING--good and bad. There's scarecely a figure in the Scripture that doesn't give us SOME lesson in how NOT to live.
There isn't always a clear 'commandment' in scripture concerning every decision we're faced with in this life. That's by design! God is building character in us...conforming us to the image of His son. We're not there yet.
You don't seem like the kind of young man who is out every weekend shooting heroin in your eyeballs and shagging prostitutes. None of us want to be the 'cause' of you becoming that guy, I'm sure. But part of what builds the experience you need is taking some wrong steps, so we also don't want to be the ones to deny you that hard won (and most valuable) wisdom by laying down laws for you to follow--like your fundie friend, who I'm sure is hoping to keep you out of Hell. I know from your first post in this thread you already possess some wisdom in this area.
To me, the scripture that covers your life-experience (as I vaguely imagine it via the internet) doesn't have to do with music, dancing or anything related to that. It has to do with maturity in the faith. You're going to get to a point eventually when you don't need to consider all these things...you will KNOW what you need to do. I am pretty sure you're not there yet...otherwise you wouldn't be asking the question. There are issues for all of us that put us right there in the same boat with you. I have no doubt of that.
I typed all that long enough to decide that I am not going to give you 'an answer' until you answer some of mine. OK?
1. Forgetting what your friend said, what do YOU think about this oppurtunity? Is it a good one? Are there dangers involved in it--obvious and clear in your mind?
2. If you learned that what your Fundy friend says is true, would it change your life in any way?
3. If you learned what your Fundy friend said was hogwash, would it change your mind about music?
4. What do you believe the Spirit of God is 'influencing' you to do?
Try those on, if it suits you, and maybe 'we' will have a better handle on what 'wisdom' to offer you in return. After we do, assuming we can, Jesus is still Lord and you still have to decide. You'll decide according to the way God has already foreseen. No circumstance changes from what already exists.