You are at a friends house when a friend of a friend mentions they will be taking their first uber ride home which will cost them around $20. This person does not know of any such promotional code discounts.
But you know from your experience on ozbargain that you can either:
Get them a generic $25 off first ride code (Satisfaction of getting them a bargain, helping them out)
or
You could give them your $10 off referral code so that you then receive $10 credit to your uber account and they still get a discounted ride. (Well if it wasn't for you they would be paying full price anyway so you both benefit from this)
Which do you do?
The extremely grey area here is the phrase "friend-of-a-friend" (FOAF).
If it was an actual friend of your own, almost everyone would surely alert them to the $25 credit code. But a FOAF can take many forms. Sometimes you may not even like a FOAF at all, and sometimes you may actually dislike them them a lot. Conversely, other times you might take such a 'shine' to a FOAF that you would likely offer to give them a lift home (etc.) yourself, thus sacrificing a potential 10 clams of UBER-credit for a potentially much more substantial (albeit non-monetary) reward; a 'new friend' ;)