Halloween
Even though it's stated they never celebrated Halloween, with all of Arthur's outbursts, I think that episode where he forbids the holiday in a house he doesn't pay bills in he would be in a retirement home that same night and Carrie would join him since she *even though they don't celebrate it* never said hey don't put up Halloween decorations my dad will fly off the handle...but that's only if I lived in the fictional Heffernan house