You find random marker colorings on the wall.
A blur of random nakedness streaks by you at a birthday party (in public).
Yes, that is my child.
All the books on the bookshelf have been pulled down.
Your sister's make-up is dumped out all over her cosmetics drawer after an afternoon visit.
(Thankfully I have the best sister in the world who emailed me this photo after finding the mess and told me she actually thought it was a little bit funny).
You find random hair clippings on the floor.
You might have a 2-year-old if all of these things have happened within 5 days of each other.