Tell 'em there are a lot of people outside which have them and want to spend it. Start an investigation, how willing bitcoiners are to spend 'em and what products they want to purchase. Say them, you will advertise them in the community.
q: would you invest more $ in electronics/food/biere, if you could pay with bitcoins?
q: would accepting bitcoins be an attribute of a company which encourages you to chose it as your allday-retailer?
Bitcoins are popular mainly because 99% of people that are using them are interested in making quick money from them. You simply can't explain a concept to everyone and many businesses are only interested in dealing with "live" currency ( cash ), because they can invest that money or use it to pay for workers, to order new items and stuff like that.