"Yeah, on the third night after Karkus was killed we crept outta the cave we'd bin hidin' in an' headed back down inter the gully, keepin' our eyes skinned fer the Death Eaters. Got inside a few o' the caves, no go - then, in abou' the sixth one, we found three giants hidin'."
"Cave must've been cramped," said Ron.
"Wasn' room ter swing a Kneazle," said Hagrid.
“Wasn’t room to swing a Kneazle” is a wizarding expression indicating very tight quarters. Hagrid says it in reference to a cave he and Maxime entered with three wounded giants in it.
The phrase is a Wizarding take on the Muggle phrase "Wasn't room to swing a cat," which is of nautical origin. While some sources say that the cat in this phrase refers to cat-o'-nine-tails, a type of whip, in fact the phrase was in use thirty years before that type of whip was named, so the cat involved was almost certainly a real cat. Poor thing. In the wizarding version, the cat becomes a Kneazle, which is a magical breed of cat. I can't imagine a Kneazle -- or any cat for that matter -- would take kindly to being swung around by the tail.