Mine involves birthdays/anniversaries.
BirthdaysDad: July 4
Mother: Memorial Day (back when it was always May 30th)
Me: Valentines Day
Niece: Halloween
AnniversariesParents: Labor Day
Sister: September 11 (not really a holiday, but now it's remembered rather well)
My sister was the oddball on birthdays. She missed Armistice Day (what is now Veteran's Day) by 2 days. Loser!