Green’s Dictionary of Slang

1. the penis; thus well-trapped adj., well-endowed.

1654		Mercurius Fumigosus 19 4–11 Oct. 170: The good man putting over his arm, and feeling for his Wives hand, found it under the Painted Cloath, upon her Brothers Trap-stick.
1660		‘Megg. Spencer’ A Strange and True Conference 5: These females do every one of them buss the end of his Trap-stick as he lyes naked upon his bed [...] T[arse] upwards.
1660		Wandring Whore I 13: By the help of a well-trap’t Doctor, was perfectly cured.
1675		C. Cotton Scoffer Scoff’d (1765) 283: Well, well! but he were best to take heed / How he attacks my Maidenhead: / His mighty Trapstick cannot scare us.
1696		Motteux (trans.) Gargantua and Pantagruel (1927) II Bk V 677: Ere long, my friends, I shall be wedded, Sure as my trap-stick has a red head.
1772		Bridges Burlesque Homer (3rd edn) 188: With his trapstick on the cock / Ready to give her a good knock.

2. usu. in pl., legs, esp. thin legs.

1714		J. Addison Spectator No. 559 36: A foolish Swop between a Couple of thick bandy Legs, and two long Trapsticks that had no Calfs to them .
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue n.p.: Trap sticks, Thin legs, gambs: from the sticks with which boys play at trap-ball.
1811		Lex. Balatronicum [as cit. 1785].
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1834		‘Jack Downing’ Andrew Jackson 67: He’d bin thrown off his trap-sticks .
1837		‘Nights At Sea’ in Bentley’s Misc. May 483: Nobody as ever had seen him could forget them ‘trap-stick legs.’.
1845		D. Corcoran Pickings from N.O. Picayune (1847) 43: I’d lay any fellow flat as a pancake that dar say trap-sticks to ye.
1950		S. Murphy Stone Mad (1966) 136: Down his gullet it went while you’d be saying trapsticks.