Take every fucking thing that isn't screwed down or in the particulars - light bulbs, loo seats, toilet roll holders, lamp shades, everything you can reasonably get away with.
And hide nuts in the loft and in the flowerbeds so squirrels get in and dig around.
Take beading from around units in double glazing and pierce spacer bar sealant with pin so all the units go misty.
Tear holes in mastic around bath and shower so they have leaks when bathing or showering.
Go to pet shop and buy a few dead mice for feeding your pet snake and leave under floorboards or at back of cupboards.
Gosh sorry am getting a bit carried away!