Education and the like

So apparently someone told one of the girls at the restaurant that I have time to tutor people (I really shouldn't complain about my neighbours). So she asked me whether I could help her friend's son with his spoken English so he can pass the English exam to get into university here. I told her I'm a bit short on time lately, but I'd think about it. She suggested that all I needed to do (for $20/hr) was just bring him along when I go out to dinner with my friends and let him sit and listen to us talk. Hello?! Creepy. Apart from the fact that I don't know the guy and I wouldn't be able to talk normally with a stranger listening to my private conversations, what sort of language would he be picking up? Not textbook English, that's for sure.