Green’s Dictionary of Slang

(Irish) a working-class person with delusions of grandeur, esp. as shown in their dress sense.

1994

C. Fitz-Simon Boys n.p.: A ‘chrissie’ became a word for a lower-class person with delusions of grandeur, and the phrase, ‘It suits ya, Chrissie!’ [...] is still used to compliment someone wearing an item of clothing which patently does not suit them [BS].