The basement stairs, which are way more exciting than the regular stairs.
The process of scooping and disposing of their poop, which they have to run over and supervise whenever I do it (where supervising = getting in the way).
Pens, especially if on the table. A pen’s proper place is on the floor, of course.
What the humans are eating and/or drinking. Best examined from the vantage point of the table.
Human feet, under a duvet, at 5am. Pounceable deliciousness.
Tails, which are a constant mystery, in spite of having one each.
A piece of dry cat food that has accidentally skittered across the kitchen floor and is much more alluring than all the rest of the cat food in the bowl.
The breeze coming through an opened window.
The bath, empty (for playing in) or occupied (utterly flabbergasting).
The toilet, ditto; they must come over and inquire into exactly what I might be doing if sitting there.
The inside of the dishwasher.
The inside of the clothes dryer.
Drawers – how they work, what’s inside them, what might be behind them.
The freezer, on the bottom of the fridge, the most mysterious drawer of all.
The sliding closet doors. They clearly operate by witchcraft and must be stopped at all costs.
Empty tissue boxes, to be examined closely, from within, at a cat’s peril.
Shopping bags: enemies, to be defeated.
Napping. More investigation required. Haven’t got to the bottom of this yet. Will get back to you with our results.