Take all batteries, drain them of charge, and if inside remote flip polarities as well.
Separate out and take all but 1 Ply of toilet paper on the rolls, reroll them and put them back.
Turn all staples in stapler upside down.
Rearrange/randomize car+house keys on key rings.
Replace all glasses/contacts with different prescriptions.
Change all medicine labels for rectal use only labels.
Set alarm clocks for odd hours of the night.
Take carpet off the floors and reapply it in the bathroom and kitchen.
Steal water line from all sinks and toilets.
Cut shower head cord in 2, take the shower head (or leave it and a note saying they got a wireless upgrade)
Steal various food items at random, and all cooking spices/herbs.