(as) crafty as a fox / (as) cunning as a fox / (as) sly as a fox / (as) wily as a fox – умный и хитрый
Exceptionally clever, cunning, or shrewd, especially in devious or underhanded ways.
My friend is as crafty as a fox.
a stone cold fox – нереальная, красотка
Someone who is very attractive and appealing, usually a woman.
A: "Wow, that girl is gorgeous." B: "I know, she's a stone cold fox."
crazy like a fox – умный, хитрый и сумаcшедший
Very clever, cunning, or shrewd while appearing foolish or mad.
Our boss is crazy like a fox; her daredevil schemes always sound like they'll bankrupt us, but they invariably bring in a huge profit.
fox guarding the henhouse – "лиса охраняет курятник". Человек, который может воспользоваться ситуацией.
A person likely to exploit the information or resources that they have been charged to protect or control.
My sister is going to put her ex-convict brother-in-law in charge of her business, and I'm worried he'll be like a fox guarding the henhouse.
fox trap – «лисий капкан» (машина, которая привлекает девушек)
slang A car modified in such a way that it will (ideally) make the driver appealing to women.
We need a fox trap, not your ancient station wagon. No self-respecting woman would want to be seen in that thing!
fox's sleep – лисий сон (спать, но слышать все вокруг, следить за ситуацией)
A state of apparent sleep (or feigned indifference) in which someone is actually aware of everything going on around them. Alludes to the idea that foxes sleep with one eye open and thus are always at the ready.
I think Amy is just in a fox's sleep, so be careful what you say right now.The best way to get gossip on these trips is to be in a fox's sleep.
shoot (one's) fox – мешать чьим-то планам, подрывать планы
To undermine or thwart someone's plans, efforts, or ambitions by taking action that pre-empts them or makes them redundant. Primarily heard in UK.
Congress may have shot the president's fox, though, with a bill that he cannot politically afford to veto, but which leaves him with no opportunity to pass his signature healthcare plan.