great for when the cheating ex is out for the weekend and you still have the key. get some real fast growing seeds, like watercress(the stuff that comes with those chia pets) and put it allover the carpet, ater well and voila you have a indoor carpet.
got to the library or internet cafe(better not in your town) to do the next one.Use their computer and put up a add for whatever incredible cheap and put their # down.
some more classics:
rub a bar of soap on the windows
flaming bag o poo
grap their bike and a rope thow rope ove large tree attach bike a pull the bike into the tree .
put saran wrap over toilet seat.
switch sugar for salt and vice versa
itchpowder  on the toiletpaper
if you use liquid soap put food coloring in it
a thumptack under their favorite seat in the house