Get 500 or so small audio playback devices, record the first two bars of Tubular Bells on them, change the pitch and tempo of each one slightly, set them all to repeat at different frequencies, some of which may only do so every week or two. Hide them all over the house.
I'd switch the pillows on each side of the beds.
I'd set each hanging picture frame crooked.
On the home computer I'd leave a search page open "Advice on how to tell your wife you are gay".
I'd do an upper decker.
I'd replace the regular tea bags with green tea bags.
I'd smear shit on the underside of the.kitchen table.