( informal ) to know / tell sb some useful, interesting or surprising information about sb/sth :
She's been married five times, so she knows a thing or two about men!
( informal ) to know / tell sb some useful, interesting or surprising information about sb/sth :
She's been married five times, so she knows a thing or two about men!
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005