Atticus likes to make the most of the 4th of July without spending a ton of money on fireworks. And since our kids are generally easily pleased, that's not hard to do. He sets up a few exposive-thingies and then runs away, cartoon-style, to get the girls laughing.
And laughing, hard, is what Betsy was doing when she said:
"Oh, Daddy! I love your holiday spirit!"