My youngest has a birthday coming up, and the big two were asking about her birth date. D was born on Easter Sunday two years ago, so I was explaining that just because it was Easter that year, does not mean that her birthday will be on Easter every year.
I went on to give examples of holidays that rotate days, like Thanksgiving, and Easter versus the holidays that are fixed on a certain date, like Christmas, and Valentine's at which point, the middle child pipes up. "What about the 4th of July? Is it always on the 4th of July."
I love the funny things kids say!