As part of a grammar exercise, all students were asked what their favourite way to relax is and why. A depressingly high amount of students chose "sleeping". This is because most of them get up at 5:30~6:00 to catch the train to school and then study until 9:00 or 10:00 at night every freaking day, but this one response is especially bleak:

Not only did he start a sentence with a capitalized "because" AFTER I TOLD THEM NOT TO, but his favourite pass time is turning off his mind. God! That's Lowbott showing his disgust, there, by the way.
Now, just after Christmas I did what every good ALT does: dedicate an entire class to "what did you do for your winter vacation?" lessons. One student wrote:

Powers, eh? This may be an example of the semantic differences between the English 'raw power' and Japanese 'energetic power', but the student obviously wasn't aware that 'powers' is pretty much reserved for high ranking corrupt politicians and superheroes. But, reading this, this is precisely what came to mind.
Finally, I've posted this before, but I think this is the best thing I've ever got from a student:

A bit hard to read my scrawled handwriting, but it says, "Hello! Today I'm going to show you a pig doll. It is very cute, isn't it? It's about 2000 yen. It's name is "Boo-chan". He is very pretty because his nose is big. [Editor's note: I guess that's why Japanese people find me so pretty]
"My grandmother gave me a pig doll in Safari Park for [sic] years ago, but there aren't any pigs in the park.
"Do you like pigs? I love pigs. Pork is delicious and pigs are a lot of fun. Thank you."