That would be quite interesting! I'm very curious as well. It's a great way to find people asking "What's fun to do in *your city*?", which is a prime group of individuals our dances are hoping to find in my opinion. I think Rich makes a good point that 50% discount would not be very attractive, but I think the real benefit is in fact simply getting people to hear that contra is even a thing. It's essentially free advertising in a way given that I know many dances will have some 50% of "bring a friend free" promotion that are effectively doing this but without the huge outreach that Groupon provides.