What ia chu?
chủ = lord
nhật = sun
chủ nhật = Sunday
It seems that this was translated from the English term.
I think that similar with Hanzi 主日 https://zh.m.wikipedia.org/zh-sg/%E4%B8%BB%E6%97%A5
Doesn't it sound like the speaker is saying 'Không lai' instead of "không ai"?