Whether you're above or below the drinking age, you aren't safe from those who insist on discussing the different qualities of expensive or cheap wines. Wine snobs are known to have been created in order to inform those who don't care about the "smokey tastes," "dry and or tart grapes," and that "this wine right now is even better than the one I said was the best yesterday."
I've met wine snobs from a variety of ages including my own family members, so here's to you grandpa. I know they are only trying to spread their no doubt "useful" knowledge of squashed, alcoholic grapes. But, I can't help but say to my friend who went on for 10 minutes about the artisan craft of a box wine he bought at a ShopRite, I just don't care.
My mom is in the top ranks for a brewery located in Los Angeles. When I was a teenager she started explaining the science behind how beer was made and also explained wine. She talked about how some people love the creation of both so much that they even brew and vinify their own alcoholic beverages.
Of course, they're entitled to explaining their home brewery, sounds pretty impressive. Once it turns into a long description of the "smokey afterbirth" of a wine, as said by Michael Scott from "The Office," I can't take it seriously.
There are a few qualities that you can use to sound knowledgeable about wine without being obnoxious. If a wine has legs, it means it's high quality and that it slowly drips down the inside of the glass.
The reason a wine glass is never filled to the top is to let it breathe, and if someone pours you a cup of boxed wine and then goes on to tell you how you can taste its "smokiness," pour it out and grab a beer.