Not so long ago, grandmothers were confined to knitting sweaters in their rocking chair. But these days, the silver-haired set is just as active as anyone else. (Or at least that's what we gather from all those TV commercials for heart medication.)

Jimmy Fallon celebrated these "new school" grannys by introducing the  hashtag #MyGrandmaIsCool on Twitter Wednesday. Within five minutes this became a  international trending topic, with thousands of responses. Fallon read some of his favorites on Thursday's episode of 'Late Night.'

So what did we just learn here? Well, that grandmas are a terror on the road, and not just because they drive under the speed limit in the left lane. But we think our favorite Tweet was the one about the grandmother who tailgated at the Buffalo Bills game. Granny really knows how to party.