Once upon a time, a few months into our tenure in a splendidly new executive townhouse (hey, that's what it said in the Zoopla description, but then it was in South Norwood) we obtained two new kittens (our old cat had just died, and whereas the plan was to take a break from pet ownership and go to NZ for a month, much pining resulted in new kittens instead and we've still not gone to NZ).
To minimize the potential for kitten-derived mischief with computer cables and the like, we kept our offices on the top floor closed. So one Saturday afternoon while we were out taking a stroll through the Kentish countryside one of those kittens took the opportunity to spend several hours attempting to tunnel under those doors. Through the carpet. The new executive townhouse carpet that had cost many, many thousands of pounds (honestly, one the big disappointments of being a grown-up is that you have to spend your money on crap like carpets).
That's one of the many reasons that kitten came to be known as Bad Cat.