Green’s Dictionary of Slang

1. (also string-o-beans) a tall, skinny person; thus as a nickname [note D’Urfey, Pills to Purge Melancholy (1719), of a woman: ‘The one thin and lean, As a Garden French Bean’].

1874		‘A.P.’ [Arthur Pember] Mysteries and Miseries 357: Mary Rogers, alias ‘String-o’-Beans’ [...] a great, gaunt woman, nearly six feet high.
1912		L.A. Times 14 Nov. 34/3: Mae Melville calls her elongated husband [...] her ‘human stringbean’.
[1914		Ade ‘The New Fable of the Aerial Performer’ in Ade’s Fables 197: She had abolished her Shape entirely and [...] tried to model herself on the lines of a string Bean, slightly warped by the Sun].
1920		T. Thursday ‘Missed in Missouri’ in Top-Notch 15 May 🌐 ‘So I begged you to marry me, you shrimp!’ she raved [...] ‘Me—falling for a piece of string like you.’.
1923		Wodehouse Leave it to Psmith (1993) 507: Lemme tell you it’ll take someone better than a half-baked string bean like you to put one over on me.
1932		R. Fisher Conjure-Man Dies 271: You’ good as out, stringbean.
1946		Nottingham Eve. Post 15 Nov. 4/6: There are three main types of men — the fat man or butterball, the bone and muscle type, and the stringbean.
1949		A. Hynd We Are the Public Enemies 99: Floyd teamed up with George Birdwell, a tall stringbean two or three years his senior.
1956		‘Ed Lacy’ Men from the Boys (1967) 16: Lawrence had been a quiet stringbean who thought I was the greatest thing ever.
1969		C. Himes Blind Man with a Pistol (1971) 139: A black stringbean wearing a floppy white hat came cautiously from 125th street.
1970		P. Roth My Life as a Man (1974) 317: This tall string bean with a crew cut.
1981		J. Wambaugh Glitter Dome (1982) 136: Wondering if Marty had spotted the skater, when another fifty-five-year-old stringbean flew by.
1997		Mad mag. Nov. 33: No wonder you always have to play second banana to this string bean.
2001		(con. 1964–8) J. Ellroy Cold Six Thousand 207: Forty Cubanos — porkers and stringbeans — jail recruits all.
2005		J. Stahl I, Fatty 190: They signaled for some uniformed string bean to open the doors.
2013		T. Black Ringer [ebook] n.p.: I’m only sixteen, string bean they call me .
2017		Boston Globe (MA) 2 Sept. A1/2: Cross-country runner Jope McConaughty, known by the trail name Stringbean.

2. attrib. use of sense 1.

1928		Derby Dly Teleg. 14 July 1/4: The ‘Stringbean Silhouette’. US Girls’ Craze for Slimness.
1979		‘Iceberg Slim’ Airtight Willie and Me 52: Sue and her daughter, with Sue’s string bean Cajun husband.
2000		J. Hawes Dead Long Enough 157: A couple of stringbean, muscled girls, hammering away at the rolling rubber floor.

3. (US black) a very thin, long penis.

1980		E. Folb Runnin’ Down Some Lines 154: Vocabulary that addresses itself to the size and shape of the penis — string bean (skinny penis).
1999		Roger’s Profanisaurus in Viz 98 Oct. 27: stringbean n. A long, thin, probably green penis.