Or you could just say 'Look dude, it is really important to this project that nobody fibs about their experience and expertise. You have told me that you were a Royal Air Force fighter pilot and you look and sound like a dripping Walt. So, **** me not. Are you on the level?'
The trouble is, he might not like you.
I'll come and do it for a 4 bottle lunch.
(I haven't got any mates either)