If both girls have a snack bowl Kate's will suspiciously empty at the speed of light and Kendall's will overflow.
Kate is pretty resourceful...beware of silence when it comes to her. For instance today I found her in my bathroom with the stool from Kendall's room pushed against my bathroom counter. She was sitting on the floor surrounded by the contents of my make-up bag.
Beware gaping pants. If your pants gap at all in the back Kate will laugh at you. Then she will proceed to put her hand down the back of your pants and say, "BOO-TEEE"
It's best to just keep bathroom doors closed at all times. Kate will play in the toilet and today I found both girls in their bathroom surrounded by an entire roll (and another half roll) of unwound toilet paper.