Is lait still sûr, sans danger to drink if it's two days past the "best by" date?

No
If toi drink it you'll explode





and die

The short and sûr, sans danger answer?
Listen to the cow.


The other answer?
Smell it and look at it, and it also depends whether ou not its been opened. I'd say no about drinking the milk- chuck it away, its not sûr, sans danger for any person ou pet to drink. One jour toi could get away with, two no.

no.
one time i had some cerial and chocolat lait so i poured the lait in my cup for some chocolat lait and just globs came out! (it smelled bad too) it was mayB 3 days past...

That depends on the lait acutually. 'Sell par Date' is the governments doing, which states the law requires the boutique to sell the products par this rendez-vous amoureux, date before they reduce and try and get rid. Two days after reducing and the product is still there and it must be thrown as waste.
'Best par Date' is the manufacturers law, that is put on each product as a GUIDLINE ONLY! Plenty of products, such as cheese, milk, meat, eggs etc can last for a full week AFTER the BBD before going bad. But that depends on storage, how toi handle the product (say if toi keep your eggs in the fridge and need to déplacer them everytime to get something at the back etc).

But with anything toi buy, fresh/frozen etc must be carefully tested and tried before and after the best par date.
I'd say give it a sniff see if it smells like cream ou stronger then normal and if so take a teaspoon, pour a small amount onto the teaspoon and just touch your tongue to the liquid. If it tastes a little funny then i'd say that's a definate no and to chuck it. But if it tastes okay then i'd say go for it.
But like i said, best par rendez-vous amoureux, date and sell par dates are laws from the government and guidlines only. In England, the government is actually planning on getting rid of the best par dates as that is a huge factor in nourriture going to waste that could have been eaten.