Fig.: to be in a very small, confined space

It looks like that in big cities the smaller the apartment the better it sells, but some apartments are so small that there isn't even enough room to swing a cat

Sembra che nelle grandi metropoli gli appartamenti piccoli si vendano meglio, ma alcuni appartamenti sono talmente piccoli che non c'è spazio nemmeno per rigirarsi

The rental agency offered us a luxury motorhome, large and comfortable, that could sleep up to 6 people. In reality, when just the two of us stepped in, we realized that there was barely room to swing a cat

L'agenzia di noleggio ci aveva offerto un camper di lusso, grande e comodo, che poteva alloggiare fino a 6 persone. In realtà, quando noi due siamo entrati, ci siamo resi conto che non c'era spazio nemmeno per respirare

The cat mentioned in this expression has nothing to do with real felines. The "cat" is a cat-of-nine-tails, a type of whip used to discipline sailors on old sailing ships. The cat-of-nine-tails has one handle to which are attached nine thin strips of leather. It would be used to administer lashings and the whippings would take place on the deck, because below deck there was not enough ceiling height to swing a cat-of-nine-tails