Russian ⇄ English

кто бы мог подумать stresses
gen.	of all people (to show that a person is unlikely/surprising to be seen in such position/role – he is, of all people, is CEO now Damirules); who would have thought of it (Damirules); what do you know (malt1640); lo and behold (I went into a bar just next to our hotel and, lo and behold, who should I see sitting there but Jim Gibson. 4uzhoj)
cliche.	who would have thought
idiom.	that's a turn-up for the books (Well, that's a turn-up for the books – I never thought he'd get the job. • Well this is a turn-up for the books. After almost four years of banging the BlackBerry 10 drum it seems the Canadian firm has finally admitted defeat, launching its first Android smartphone. 4uzhoj)
inf.	who could have thought
sarcast.	go figure (a sarcastic way of saying "Who would've figured that out?": A: "The teacher didn't give anyone A's even though the test was easy." B : "Go figure." (It's sarcastic because the teacher never gives A's) Tamerlane)
кто бы мог подумать!
gen.	of all places
amer.	I'll be damned! (Well, I'll be damned! The Red Sox lost the pennant. Val_Ships)
humor.	shocker! (Bartek2001)
inf.	who knew? (в т. ч. сарказм SirReal); who would have thought? (восклицание удивления, изумления; ответ не ожидается); whodathunkit! (Wakeful dormouse)
slang	Fancy that! (Interex)
кто бы мог подумать?
gen.	whoever would have thought it? (Anglophile); who would have thought it?
кто бы мог это подумать!
gen.	who ever would have thought it!

кто бы мог подумать: 7 phrases in 3 subjects

General	4
Humorous / Jocular	1
Informal	2