old hat

Từ điển Việt Anh Việt 4in1 - English Vietnamese 4 in 1 Dictionary

ˌold ˈhat BrE AmE adjective [not before noun]
if something is old hat, a lot of people have said or done the same thing before and it is therefore not new or interesting:
Most of this is probably old hat to you, isn’t it?

old+hathu

◎	['ould'hæt]
※	tính từ
	■	(từ lóng) cổ lỗ sĩ, không hợp thời trang
◎	[old hat]
〆	saying & slang
	■	an old idea or fashion, passé
		☆	Sunday picnics are old hat. They're not popular now.