In LADY CHATTERLEY'S LOVER, Mellors the gamekeeper introduces 'John Thomas' to 'Lady Jane'. I can't say I have come across the latter as a term for vagina or pudendum elsewhere: has anybody? Or did DHL just make it up?

Not the first time I have come across an American stating that 'randy' is an exclusively UK word, but I grew up thinking it an Americanism: IIRC [tho it's going back about 65 years] I first came across it in Steinbeck's The Grapes Of Wrath. I don't, btw, think it is connected with the name Randy, as Roger & John Thomas do derive from names in a attempt at humour[?], but rather is an independent word cognate with 'rant', from Dutch meaning to rave {& not in the party sens: oh, just get embroiled in words/derivations and see where you end up!

YAY: FOUND IT! ~~~ Minds me of a story they tell about Willy Feeley when he was a young fella. Willy was bashful, awful bashful. Well, one day he takes a heifer over to Graves' bull. Ever'body was out but Elsie Graves, and Elsie wasn't bashful at all. Willy, he stood there turnin' red an' he couldn't even talk. Elsie says, 'I know what you come for; the bull's out in back a the barn.' Well, they took the heifer out there an' Willy an' Elsie sat on the fence to watch. Purty soon Willy got feelin' purty fly. Elsie looks over an' says, like she don't know, 'What's a matter, Willy?' Willy's so randy, he can't hardly set still. 'By God,' he says, 'by God, I wisht I was a-doin' that!' Elsie says, 'Why not, Willy? It's your heifer."
— John Steinbeck (The Grapes of Wrath) ~~~

How about that for research!

~M~