Green’s Dictionary of Slang

a street-walking prostitute.

1859

‘Scene in a London Flash-Panny’ Matsell Vocabulum 100: Say, Harry, will you suffer yourself to be made a two-legged stool of by a flag-about?

a street prostitute; thus flaghopping adj.

1832		S. Lover Legends and Stories 191: ‘How do I know that, you flag-hoppin’ jade,’ says he.
1833		‘The Girl and the Country Man’ in Rummy Cove’s Delight in Spedding & Watt (eds) Bawdy Songbooks (2011) III 115: When he was coming down Fleet-stree[t] at night, / A dainty flag-hopper was on the loo[k] out.
1841		‘Jack Sheppard & the Carpenter’s Daughter’ in Gentleman’s Spicey Songster 11: O then she was glad to turn on the town, / To a common flag-hopper soon she came down.
1850		Man of Pleasure’s Illus. Pocket-book n.p.: These of whom we have made mention are new importations, and have much improved the breed and condition of the native flag-trampers, as also the [...] treatment of the British bawds to their wretched labourers.
1880		‘Sally’s Mistake’ in Pearl 10 Apr. 15: You have a gay woman in keeping – some painted little bitch or flaghopper.
1880		‘Overheard at the Aquarium’ in Pearl 13 July 38: Damn it! all the same flaghopping faces, not a fresh bit of cunt here.

(US prison) recreation that takes place in an open space on the bottom floor of a cell block.

1982

Rapid City Jrnl (SD) 17 Jan. 31/1: An inmate and his kid discussed escaping. Their plan [...] to pose as fish during flag rec, enter the fish tank and then climb out of a vent.