Green’s Dictionary of Slang

1. (US) a native of Mississippi.

1845		St Louis (MO) Reveille 14 May 2/4: The inhabitants of Mississippi [are called] Tadpoles [DA].
1866		Montana Post (Virginia City, MT) 28 Apr. 4/1: The inhabitants of [...] Mississippi [are called] Tadpoles.
1871		Semi-Wkly Louisianan 31 Aug. 1/3: The Nicknames of the States [...] Maryland,crawthumpers; Michegan, wolverines; Minnesota, gophers; Mississippi, tadpoles; Missouri, pukes.
1885		Whitman ‘Sl. in America’ in North Amer. Rev. Nov. 433: Those from Maine were call’d Foxes; New Hampshire, Granite Boys; [...] Mississippi, Tad Poles . . . Oregon, Hard Cases.
1905		El Paso Times (TX) 12 Nov. 16/4: Mississippi is the ‘bayou’ state and its citizens are ‘tadpoles’.
1909		J. Ware Passing Eng. of the Victorian Era.
1946		C. McWilliams Southern Calif. Country 172: Marylanders are ‘crawthumpers’; Kentuckians, ‘corncrackers’; Mississippians, ‘tadpoles,’ and so forth [DA].

2. (US black) a young inexperienced boy.

1949		‘Josephine Tey’ Brat Farrar 217: Brat wished that this tadpole creature was not sitting between himself and Eleanor.
1973		C. Himes ‘Baby Sister’ [screenplay] in Black on Black 94: Don’t kick that boy; he’s just a tadpole.
1978		W.D. Myers It Ain’t All for Nothin’ 9: ‘I don’t have to be reporting to no tadpole how I feel all the time’.
1992		(con. 1910s) F.M. Davis Livin’ the Blues 41: ‘You might fool these tadpoles,’ he went on waving his hand toward the younger boys [...] ‘but you gotta put somethin’ straighter’n that for an old ace like me.’.
2013		W.D. Myers Darius & Twig 24: I probably didn’t hurt the tadpole, but she just gets upset if one of us cries.

3. semen; also attrib.

1997		Observer Life 16 Mar. 86/2: Spermless men end up in the doghouse more often than your full-count tadpole carriers.
1999		Observer Rev. 7 Nov. 13: Sam is terrified he might be found to be lacking in the tadpole department.

4. (N.Z. prison) a prison novice [‘[S]uch an inexperienced inmate is like “a tadpole thrown in with a tank full of sharks” ’ Looser (2001)].

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 184/1: tadpole n. an inmate new to the prison, serving his first sentence.