I tell them if asked for free miles that miles have value of 2 c each and if I sold it to them I could have my account locked.
If not asked for them, I give miles to friends and family. After a while, you know who your real friends are by the favors they do for you back.
The happiness of free elite status, upgrades when not expected really make people know how much you appreciate them.
I just sent 2 sets of friends and family last week to SIN for the cost of 1600$ each plus taxes in LH F -ORD_FRA_SIN, a remnant of the miles I bought in April May with the double bonus snafu (212k @1cpm cost for each account x 11) for sharing miles on US. (alas now gone - I should have kept quiet)