I explain it-but generally not using myself as an example.
I give them the generally held definition and a link or two (like www.lovemore.com
mentioning the online magazine or www.xeromag.com
mentioning the articles under polyamory)
If I think that they are REALLY that "unaware" I will actually go to the articles themselves and supply the specific links to the pertinent articles instead of leaving them to open the first page of xeromag and freaking out because the words bdsm, poly and only god knows what else that might freak them out are written there.
I figure knowledge is better than ignorance, even if they remain a jerk....