I tell him Bitcoin is a digital currency, which has great potential as investment on long term, although there are always risks implied. Moreover, I talk about where he can purchase Bitcoin and where he can store his coins safely. If I identify he is interested on the subject I may go ahead and continue telling him more details about Bitcoin, but if he doesn't display any significant interest, I just let the conversation vanishes away, so we can move to another subject.

If he has any more questions about Bitcoin, I feel happy in answering them with the knowledge and experience I have acquired so far along the years in this industry. There is so much to say about Bitcoin, but we have to do it step by step, otherwise the conversation might not be interesting for friends.

Since it's something people are getting in touch for the first time, informations provided must be basic, so they can start understading it properly.