Beware Of Tenant - Static Cling
Strike fear in the heart of your landlord! Make sure Murray knows not to test your patience because you know your local tenancy laws and shall not be trifled with!
Admittedly, these look better on single-pane windows but the venn diagram of slumlords and single-pane windows is a circle.
4 Inch by 4 Inch static clings. Sticks without an adhesive from the inside of the window so your parasite (probably) can't peel it off while you're sleeping or use it as an excuse to keep your security deposit.