Green’s Dictionary of Slang

chuffy adj.

[dial. chuffy, chubby-cheeked, healthy]

1. chubby, round-faced.

[UK]Grose Classical Dict. of the Vulgar Tongue.
[UK]Lex. Balatronicum.
[US]Randolph & Wilson Down in the Holler 234: chuffy: adj. Plump.

2. jolly, merry; friendly (cf. chuff adj.1 ).

[UK]Flash Mirror 24: Larry and his old ’ooman had been b—y good trumps to us [...] so we’ve been quite chuffy with von another ever since.
[UK]Flash Dict. in Sinks of London Laid Open.

3. of objects, fat.

[US]L. Chittenden ‘A Stockman’s Adventures in New York’ in Ranch Verses 160: Right then I showed my money, the whole big chuffy pile.

In compounds

chuffy badge (n.)

(UK juv.) a metaphorical ‘badge’ worn by one who is exhibiting signs of self-satisfaction.

OnLine Dict. of Playground Sl. 🌐 chuffy badge (do you want a...) n. derisive comment to make to someone who has been showing off.