This shit’s the stuff of memes in the mainland.
Why is it a laugh line every time he speaks in Cantonese?
Alright so doing a little research on wikipedia, Cantonese came from and is spoken mostly in the southern part of China which includes Hong Kong, and apparently something like 95% of Hongkongers speak Cantonese. So it seems like he’s trying to mock the fact that they are outsiders compared to the native Mandarin speakers.