to have sexual intercourse; thus furgler/fergler n.
|in Erotic Muse (1992) 230: They fergie [sic] a bull and fill him full / those hardy sons of bitches.|
|End as a Man (1952) 83: A natural-born fergler.|
|(con. 1948–52) Virgin Soldiers 21: A harmless mechanic [...] quietly furgling another WRAC in the long elephant grass at the side of the garrison road.|
|Current Sl. V:3 6: Flurgle, v. To have sexual intercourse.|