Green’s Dictionary of Slang

to vomit; thus fig. cat with laughter, to laugh ‘until one is sick’.

1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue n.p.: Cat, catting. to vomit from drunkenness.
1803		‘A Pembrochian’ Gradus ad Cantabrigiam 31: to cat, to vomit from drunkenness.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1860		Hotten Dict. of Modern Sl. etc. (2nd edn).
1873		Sl. Dict.
1899		Kipling ‘A Little Prep’ in Complete Stalky & Co. (1987) 182: ‘We shall cat.’ Beetle sniffed the cheroot critically. ‘It’s a regular Pomposo Stinkadore.’.
1908		Sporting Times 22 Feb. 1/4: What did we read in ‘The Daily Mail’ about dear old George Meredith’s eightieth birthday? Why, that he ‘catted amiably.’ We are so sorry.
c.1930		(ref. to 1868) N. Kimball Amer. Madam (1981) 68: I catted it up behind a hedge. [Ibid.] 199: I was pregnant. Very much so, catting during the morning sickness.
1945		P. Larkin letter 20 Dec. in Thwaite Sel. Letters (1992) 112: If there’s one thing that makes me cat, it’s bad beer.
1946		(con. 1912) B. Marshall George Brown’s Schooldays 103: ‘What’s cat?’ Molly asked. ‘Cat’s what ruins call vomit or be sick,’ Brown said. [Ibid.] 123: There were rugger blues all round catting their gutzes out.
1972		K. Bonfiglioli Don’t Point That Thing at Me (1991) 118: Mrs Spon would have catted right there on the Aubusson.