There are two things most parents and grand-parents do not and likely never will understand: Bit-coins and fantasy sports leagues. Here are two things you can say at social gatherings to conceal your ignorance:
"Did you know that a bit-coin now is worth more than a troy-ounce of gold?" Confirmatory Link
"My grand-son, a professional gambler, has shifted from online poker to fantasy league stuff."
[Note: Speaking of grand-parents and grand-children, an accomplished psychiatrist has explained why there is such a special bond these two groups: They share a common enemy.]