Green’s Dictionary of Slang

mousetrap n.

1. marriage.

[UK]B.E. Dict. Canting Crew n.p.: Mouse-trap, The Parson’s Mouse-trap, Marriage.
[UK]J. Caulfield Blackguardiana n.p.: Mousetrap, the parson’s mousetrap, the state of matrimony.
[UK]Barrère & Leland Dict. of Sl., Jargon and Cant II 69/1: Mousetrap (old cant) marriage.

2. the vagina.

[UK]T. Duffet Epilogue Spoken by Heccate and Three Witches 42: So little cruising punk and first rate Harlot, Though one Don’s stuff t’others clad in Scarlet, Use but one Mouse-trap to catch trading Varlet.
[UK]Merry Maid of Islington 14: I’ll assist thee and save thy Mousetrap from being baited with Sir Jeffries dry Cheese.
[UK]Bridges Homer Travestie (1764) II 11: If you meet the whoring goddess / Ram thy stiff weapon through her boddice; / Take care you come not near her thighs, / For there a dang’rous mouse-trap lies.
[UK]Bridges Burlesque Homer (3rd edn) 178: Take care the gypsy’s eyes / Don’t guide to where her mouse-trap lies.
[UK] ‘The Mouse Trap’ in Flash Chaunter 30: You must know my mouse trap is not made of wire, / Like some that has got little holes – two or three; / No more than one does my mouse trap require.
[UK] ‘Origin of Copulation’ in Pearl 5 Nov. 27: Oh, give me a damsel of blooming fifteen, / With two luscious thighs and a mouse-trap between.
[UK]Farmer & Henley Sl. and Its Analogues.
[US]H. Miller Roofs of Paris (1983) 12: Her mousetrap stretches when she puts one of her fingers in with his.
[US]R.A. Wilson Playboy’s Book of Forbidden Words.

3. a sovereign [the fanciful similarity of the crown and shield (pictured on the reverse) to a set mousetrap].

newspaper story n.p.: ‘No hunter in England can clear that water,’ replies the earl. ‘It’s even betting – it’s five to two on him – it’s a monkey [i.e. £500] to a mousetrap!’ rejoins the excited girl. ‘Don’t be so slangy, Julia,’ remonstrates her father [B&L].
[UK]Exeter & Plymouth Gaz. 4 Feb. 5/6: A soveriegn has been rechristened a ‘glistener,’ a ‘goldfinch,’ a ‘mousetrap,’ a ‘new hat’ [...] a ‘remedy,’ a ‘stranger’’.
[Aus]Smith’s Wkly (Sydney) 7 June 9/6: Slang of Money [...] A sovereign is a ‘glistener,’ ‘mousetrap,’ ‘new hat,’ ‘quid,’ ‘remedy,’ ‘stranger,’ ‘thick ’un’.
[Aus]Mail (Adelaide) 23 May 23/4: The sovereign has been variously called a ‘glistener,’ a ‘mouse trap,’ [...] a ‘remedy,‘ a ‘stranger,’ a ‘bean’.

4. the mouth.

[Aus]Bell’s Life in Sydney 12 July 3/1: As for his moustaches, they are [...] perhaps the most perfect erinegerous adornments that ever graced a biped’s mousetrap.
[UK]Farmer & Henley Sl. and Its Analogues.