When England use the cleaning magic and suddenly everyone's portrait undergoes Art Evolution replacing their Narmy portraits...
I can't be the only one who laughed at America's first avatar...
Buying your healing items and food from a toilet.
Sudden Death Pillow Fight
"Found Germany's whip. It's rather worn from use..."
And his attack torture. With whipping noises.
Added bonus that early on, he locks himself in a closet, Japan hands him the whip, and then the door is replaced with a steel door. Oh, and there are some suspicious noises coming from behind the door. And Italy is nowhere to be found...
When one of the Greys is in the same room as Canada, it ignores him. Looks like being invisible does come in handy.
Also, one of the options (sadly not used) at this point is to 'pour maple syrup' on the Grey.
It does, however, come up again in a playable fan translation. If you choose it, you black out, but you still survive, along with getting a CG. Sadly, the second set of options is removed, so you don't get the gag right under this comment.
"Pretend to be the piano."
Under England's Equipment, his accessory is a "Pathetic Scone". The description is "Something that was supposed to be a scone. Very pathetic."
Spain is great at breaking the tension: when he finds the other nations trapped in a cell, he thinks someone put them in a zoo. Later, one of the Greys shows up and he's terrified, while everyone else is pretty much used to it; then a second one appears and he's even more frightened, while the others are mildly surprised.
Yet another Spain example: When the nations are picking human names, he declares himself Antonio Fernandez Carriedo... and then finds it won't fit on the paper.
When America encounters his own mochi:
America: What's this revolutionary creature?! It's fantastic!
America: It radiates such an aura of intelligence!