shagging yourself silly

Another way of saying "pissing on your own chips", "making things harder for yourself", or "shooting yourself in the foot". If you've shagged yourself silly, you've really messed things up for yourself and created a total disaster which could have been avoided had you stopped to think. This phrase takes a nod to the act of inbreeding.

Dear Tory Twat, you're absolutely shagging yourself silly by planning to build over 7000 houses on a floodplain.