How to explain to someone that you can't spot reduce fat

the amount of people that come up to me in the gym and say "what exerices can I do to get abs". Or "if I take____ will it shred my stomach fat"? I try to tell them diet is the number one part of having visable abs and that the exerices are secondary to that. And that there is no magic pill but some look at me like I'm hiding the secret to having abs.. what can else can I do to educate them on this?