牙擦蘇
This is Sai Kua Pau acting the role of Nga Chaat So, one of Wong's disciples.
牙擦蘇為黃飛鴻的弟子,其貌不揚,哨牙兼口吃,但為人卻樂天知命,性格可愛。
What distinguished Nga Chaat So were his buck teeth, his stuttering speech and his nga-chaat way of talking - characteristics which also made him likable. I don't know what is the English word for nga chaat.
nga chaat also sounds like toothbrush in Cantonese, 牙刷
Here is a dialogue in a movie in which someone asked him where his Sifu was. The dialogue is in Cantonese.
Someone: So, where is Sifu?
Nga Chaat So: Sifu has gone to call chicken ... chicken ... chicken ... chicken ... chicken ...............
Actually he wanted to say Sifu has gone to order chicken rice but the word rice took so long to come out.