caught with rem-in-re, phr. — Green’s Dictionary of Slang

caught with rem-in-re phr.

[fake legalese, lit. ‘caught with thing in thing’; Williams (1994): ‘A tr. of the Latin is used in a churchwarden’s court testimony to the effect that proof of adultery requires seeing “the thing in the thing”.’]

caught having sexual intercourse.

1650		Dialogue Between Mistress Macquerella a Suburban Whore 4: See the Chambers where you sinne / Have neither flaw, nor cranny, / No hole for any to peepe in; / For if witnessed by any / That he did you see, and rem in re / At the work of generation / By Cupids Bow, y’ are hangd, I know, / For example to the Nation.
1672		J. Phillips Maronides (1678) 130: Thy own Son, whom thou shalt get / With so much fury, so much sweat, / That thou shalt dye with Rem in re.
1728		Glass Window, or, Bog-house Miscellany (1731) C: Tis very true; for we saw Rem-in-Re through the Key-Hole [...] Feb. 3 1728.
[1732		Harlot’s Progress 57: Our Priest was so so, / And mid’st his Gifts and Piety, / Did not despise the Rem in Re.