Sadly it's my wife's brother, so I'm stuck with him. Both he and his father are 'avid flight simmers' who've never done anything more than flying around in circles in FSX.
I Had to prove to them once that the P-51 they'd bought wasn't broken and was, indeed, possible to take off successfully. I then flew it the hell out of it for about twenty minutes before landing and logging out while they just stared open mouthed. My only jab was 'If you can only fly jets, you can't really fly.'