On our most recent family reunion we were supposed to all be eating together at 8:00 AM at my wife's grandmas request (It was her 80th birthday). But we didn't eat until 9:30 because we were waiting for my SIL and her husband. While waiting nearly an hour for my SIL, other people (Aunts, MIL, etc) left to get ready. They seemed a little bothered but acted like this was normal.

My SIL rolls in at around 9:00 all ready for the day, showered, make up on, hair curled, the whole deal. While everyone else is still disgruntled, many still not showered or ready for the day, and waiting to eat because my wife's grandma wont let us eat without everyone for some reason.

Anyway, the situation was silly but she is always doing selfish things like that and doesn't seem to realize it.

TL;DR My sister in law is clueless and selfish/people can get really hangry while waiting for food.