Green’s Dictionary of Slang

painters n.

SE in slang uses

In phrases

have the painters in (v.) (also have the decorators in) [euph.]

of a woman, to be menstruating.

1963–74		B. Humphries Barry McKenzie [comic strip] in Complete Barry McKenzie (1988) 102: That’s a relief. You’ve got the ‘painters’ in.
1999		J. Randall ‘A Visit from Aunt Rose’ in Verbatim XXV:1 Winter 25: Codes that refer to blood include [...] the Red Sea is in, having the painters in, the reds, wearing red shoes, are you a cowboy or an indian? a red-letter day, and riding the red horse.
2000		P. Howard Miseducation of Ross O’Carroll-Kelly (2004) 135: I’m thinking, Uh-oh! [...] because she always gets a bit [...] emotional when she’s got the painters in.
2018		K. Lister in amuse-i-d.vice.com 25 Oct. 🌐 In1974, the American Anthropological Association published their research into the menstrual taboos of forty-four societies around the world [...] 2. That women shouldn’t have sex whilst the decorators are in.