You just wouldn't know

It's something a girl says to a guy to make him shut up.

To explain to a guy that it's something a girl does

guy:I don't get why girls are like that.
girl:you just wouldn't know

guy:You spent $100 on cds!
girl: you just wouldn't know

Nah, man, she wouldn't do that

Yeah.... That's what I fucking thought to you dumb shit.

Your fiance fuck the mentally disabled?

Nah, man, she wouldn't do that.

Doesn't she know that you would think that?

I don't know.

You DO know, motherfucker. You do know. Why, of all people, would she need to fill in at the easiest house? It's double staffed all ready and it ran with only one person for years; but the only person they could find was someone in a management position? How is that the case? Bet she told you she played board games. That's what they do. Bring them here and tell them "nobody is going to believe you're fucking a retard anyways." Why would they? It's a filthy cripple.

wouldn't you know who won the pony

refers to the story told by Jim Cornette when a local wrestling promoter , faced with declining attendance , rigged a lottery to give a way a pony so his son won it , so we did not lose money on the deal . As a result anything is is obviously rigged is referred to as wouldn't you know who won the pony .

Billy got picked to be hall monitor again .
Well Wouldn't you know who won the pony

I wouldn't touch that with a 20-foot pole

A phrase used to say that you strongly wish to stay out of the way of an argument/heavy situation and not have any involvement.

Employee: I caught Debra and Jeff having sex in the office, what the hell are they thinking?

Boss: Err, I wouldn't touch that with a 20-foot pole.

Wouldn't you know who won the pony

Implies that the previously stated is rigged; local wrestling promoter, as told by Jim Cornette, gave away a pony to increase ticket sales and, to avoid losing money, rigged the raffle to ensure his son would win the pony

Of course, that asshole was late again!
Oh, wouldn't you know who won the pony!

I wouldn't piss on him if he was on fire

phrase describing a male person that you extremely dislike

My boss is a real asshole. I wouldn't piss on him if he was on fire.

Wouldn't touch her with a 10 foot pole

A female that is repulsively skanky/ugly.
Not only would you never sleep with her, being 10 feet away is still too close.

"I wouldn't touch that slut with a 10 foot pole, unless I was smashing her over the head with it."