rinctum, n. — Green’s Dictionary of Slang

rinctum n.

[US regional rinctum, a gadget, something that has no name or which one prefers not to name]

(US black) the rectum, the anus.

1972		B. Rodgers Queens’ Vernacular 19: the rectal opening, anus [...] rinctum (fr black sl).
1989–2003		R.O. Scott Gay Sl. Dict. 🌐.