Nanged the cat

When you fuck something up so badly you have "nanged the cat"

The origin of this tale leads to Fintan Morrison who once told his group of friends that his dad had decided to put down their dying cat by suffocating it in a barrel of nitrous oxide. (a very large nang)

This has then taken the form of a straightforward insult, where " nanged the cat" is in the equivalent of "you've really fucked up" so yeah