I don't charge friends for installs, unless its a big un. Then beer tokens are accepted
Similar to that, although not a friend per se. I did a head gasket for someone very very cheap and he came back that night with a couple of his boys (pair of bitches it turned out

) saying I'd ripped him off etc... So he ran me round the block in his car and said "listen!"
I said: "um, that'll be your brake pads bro - see ya!"
Yeah, I don't bother helping people out any more.