Best proposition I ever got was when I was (much) younger.
I played in a small-time punk band and we were about a week away from going on tour in Germany.
Somebody I didn’t know very well at all who was in my Tang-Soo Do karate class, whose band played free gigs of cover songs at local student bars, said “If you write this software for free for my Dad’s business we’ll let you play a few sets with our band sometime.”
Awesome!
Not only do I get to do free software development work for the Dad (which I already get paid really well for), but you’ll let me play in your shitty student band for free too!
Double win!