Has it happened to you that at a large family gathering, your relatives ask what you are actually working on, and you end up mumbling some code language? Or that you tried to explain a friend what your research is about, and why it matters, but that you don't really know how to find the right words for it?
Here's a few little ways to make it easier:
1. Avoid jargon
Starting to mumble code language will make the attention of your friends and family vanish. They'll just nod at you and think you're doing something pretty complicated, which is for sure worth a PhD and which a normal soul can never understand. However, if you understand your topic very well, you should be able to explain it without the big words as well. Using simpler words doesn't mean the concept you are explaining becomes simpler. In fact, it challenges you to break out of the paper-language you normally use, and learn to really talk about your work.
2. Compare it to something from every day life
The National Geographic Channel typically compares sizes of building and spaces with Olympic swimming pools and soccer fields. When I showed the parents of students our experimental setup in the lab, I compared the forces in there to a number of heavy trucks concentrated on one wheel. To give them a general idea of the amount of experiments we did, I pointed out how many tons of concrete and steel had been going into the specimens already.
3. Point out the broader goals
Also related to the "So what" question. How will your research influence the world? Will it completely change the way we think about the world (rather unlikely) or will it be implemented in the machines of the future? Why should you really solve your research question? Will it have practical consequences? Don't start pulling out fancy mathematical formulas, but focus on the broader reasons for studying the problem and the possible implications of the results of your research.
4. Practice makes perfect
Practice it; doing so will make you look at your research from another perspective. Regularly talking to non-experts about my topic makes me realize time and time again what is the broader perspective of my work as well. It helps me to oversee original reasons why my research was initiated and the consequences it can have on society.