in a way that suggests sth :
He behaved as if nothing had happened.
It sounds as though you had a good time.
It's my birthday. As if you didn't know!
'Don't say anything' ' As if I would! ' (= surely you do not expect me to)
AS IF / AS THOUGH
Meaning of AS IF / AS THOUGH in English
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005