Sit around in robes, talking in Latin.
I’m totally kidding, though I at one point had my brother-in-law believing that we all really did speak Latin to one another (which would be really cool, but isn’t true).
Well, Catholics are allowed to drink, so some go to bars maybe, or have a drink at a BBQ. That could be very different from protestants, depending on the sect (though Catholics are not supposed to get drunk, that would be Gluttony). What have I done with my Catholic friends?
Watched movies at home, gone to Starbucks, had a BBQ, celebrated the Fourth of July, talked about a book we were both reading, made dinner together, gone hiking, went kayaking, road trips to see other friends, gone shopping, took younger siblings trick-or-treating, text each other, tell each other jokes.
We’re normal people. Not to say there aren’t specific times or groups where you might be discussing the Bible (usually with the catechism), prayed the rosary together, publically celebrated Fatima (which is a ton of fun), or watched the CCD kids put on a play about St. Nicholas. We’re known for our Knights of Columbus Bingo, Boy Scout Pancake Breakfasts, and Lenten Fish Fries. Generally, for fun though, it’s just hanging out together.