T-That's not how you crack eggs....
good luck with that, Marcus!
The phrasing "into the cup" suggests I should be using the ablative case, but the answer uses "poculum" and not "poculo." What am I missing?
Just the other way round: "into the cup" implies using the accusative, for something happening entirely inside the cup you would use the ablative
in poculo = in the cup
in poculum = into the cup
Marcus puer improbissimus est!
I will throw up