Green’s Dictionary of Slang

slipper n.2

[‘Derived from the ‘poorer estates’ in towns where there are always three shops – a chip shop, a video shop and an offie. People from the estate would shop, rent a video but mostly play the bandit in the chip shop wearing their slippers – never shoes, they’d walk to the shops in their slippers. Slippertown – the part of town would be then named’ (OnLine Dict. of Playground Slang, 2001)]

(UK juv.) one who looks much older/younger than they actually are.

OnLine Dict. of Playground Sl. 🌐 slipper adj. Dirty, badly dressed person who usually looks older/younger than they are eg. 12 year olds with stubble, or 40 year old that looks about 12 [...] used as in ‘I’m not going in there it’s full of slippers’ – ‘He’s a right slipper he is’.