Green’s Dictionary of Slang

mandy n.

also manny
[the spelling ‘manny’ seems to appear only in Fabian & Byrne, Groupie (1969) and was coined by them as a deliberate euph.]

a Mandrax or methaqualone tablet.

[UK]Fabian & Byrne Groupie (1997) 78: He had in fact taken a Mandy, which is a sleeper, not a barbiturate, but strong nevertheless. I told him about the Mandy kick, that you’re supposed to fight off the initial sleepiness until you can groove on the feeling that floors have turned to cotton wool and your body to fluff. You zig-zag about bumping into things, and it’s all very hilarious.
[US]Ian Dury ‘Billericay Dickie’ 🎵 Another thing with Sandy what often came in handy, was passing her a mandy, she didn’t half go bandy.
[US]Frank Zappa ‘Flakes’ 🎵 Wanna buy some Mandies, Bob?
[UK]D. Fallowell One Hot Summer in St Petersburg She went back into the kitchen to count her Mandy bottles.
[UK]Indep. on Sun. 12 Oct. 13: The pill [was] marketed on the ‘downers’ and known by the nickname ‘Mandies’.
[UK]Fabian & Byrne Out of Time (ms.) 76: ‘Here,’ she said, and handed me a Smartie tube. I peeked inside, there were a couple of mandies and other goodies at the bottom.
[Aus]P. Doyle (con. 1969-1973) Big Whatever 26: A bottle of mandies — that Mandrax to you sticlers for accuracy or what the R&R blokes called Quaaludes.