Green’s Dictionary of Slang

bum-fluff n.

also bum-bluff
[bum n.1 (1) + SE fluff]

1. the very light growth of hair on the face of a boy who is on the verge of needing to shave.

[Aus]R. Rivett Behind Bamboo 395/2: Bumfluff, a small or poorly grown moustache.
[UK]B. Kops Dream of Peter Mann Act II: A mother knows – yes under all that bum fluff he’s all mine.
[Aus]Adamson & Hanford Zimmer’s Essay 109: Now as the bumfluff darkens under my chin, I hate the thought of whiskers.
[UK] (ref. to 1950) R. Barnes Coronation Cups and Jam Jars 174: I had my tea, washed and then shaved off what bum bluff there was on my chin.
[UK]A. Bleasdale Who’s Been Sleeping in my Bed 29: Hair under his arms, bit of bumfluff over his lip.
[UK]Partridge DSUE (8th edn) 153/2: late C.19–20.
[UK](con. WW2) T. Jones Heart of Oak [ebook] I remember one young man, tall and thin, on a Norwegian tanker [...] He was blond, and wore an incipient beard such as young men do. Prof named him ‘Skywegian Bumfluff’.
[UK]Guardian G2 27 May 8: There’s nothing like growing up alongside boys and seeing the bum-fluff on chins turn into unatttractive stubble.
[UK](con. late 1940s) V. Foot Sixteen Shillings And Tuppence Ha’penny 44: Mere boys, some still had the bumfluff on their chins.
[UK]D. Mitchell Black Swan Green 272: ‘Where’s yer bumfluff, Taylor?’ Ant Little peered at my upper lip.
[Aus]T. Spicer Good Girl Stripped Bare 45: I [...] see the bum-fluffed face of a teenage boy.

2. attrib. use of sense 1.

[UK]N. Barlay Crumple Zone 3: Burton pulls on his bumfluff whiskers.
[Aus]S. Maloney Big Ask 65: Boys in bum-fluff moustaches, embroidered waistcoats and Nike runners.

3. (Aus.) empty talk, nonsense.

[Aus]N. Pulliam I Travelled a Lonely Land (1957) 231/1: bumfluff – nonsense or silly talk.

4. pubic hair.

[UK]J. Poller Reach 16: Due to the extreme angle of my neck and her bobbing backside, my nose keeps coming up against her ticklish – all-too-literal – bumfluff.

5. a term of address, whether abuse or affection.

[UK]J.J. Connolly Layer Cake 137: Listen, bum-fluff, you’ve taken my cash and what you’ve come back with has been canteen gossip.
[UK]C. Miller Salt and Honey 145: So, Bumfluff, show me this cave.

In derivatives

bumfluffy (adj.)

sparse, thin.

[UK]G. Malkani Londonstani (2007) 8: If it [i.e. facial hair] weren’t too blond, it was too curly or too bumfluffy.