This is What I Mean by Bilingual...

Teacher (me): So... what do you think Japan's international role will be in coming generations?

Student 1: Japan's role in future generations? Japan has to... (closes her eyes, buries her head in her arms) MUZUKASHII NE?!

Student 2: Yep!

Student 1: I hate this topic!

A minute after that, she was fluently articulating about it anyway. Later...

Student 1: This reminds me of earth science. I love earth science... our teacher is so funny. He is so excited about science. Every day, he goes to Sanaru-ko...

Student 2: Do you know Sanaru-ko? It's the most dirty lake in Japan.

Student 1: And he goes to Sanaru-ko every day to take samples. He told us in 100 years it may be clean again.

Teacher: Oh yeah, a friend told me they dredged the bottom there one time to try to clean it.

Student 2 (nods): It didn't work, did it?

Teacher: No. He said they dumped it all in an empty lot and everything there died.

Student 2 (laughing): Kowai!

Teacher: There's a park in my hometown that used to be a lake. One night the residents heard a noise and the next day, when they woke up, the lake was empty.

Student 1: Maji? Why? What happened?

Teacher: Well, the rock under my hometown is soft limestone, and there a lot of underground caves and tunnels. Sometimes they collapse and surface water can drain into them. It's similar in Florida, where sometimes these holes open up and swallow cars and entire neighborhoods.

Student 1 (laughing in disbelief): MAJI?! Kowai...

Student 2: Kowai!

After that they talked about their earth science teacher again in both English (to me) and Japanese (to each other).

Glossary of Japanese Terms:

kowai (koh-why): scary, frightening. Don't confuse this with kawaii, in which note the initial a vowel (a as in father) and double i; pronounce both: kah-wah-ee-ee. Or else you may find yourself insulting someone by declaring their baby to be frightening.
Maji? (mah-jee): "Really?" with a rising, "question" inflection, but has a declarative when said with a flat intonation: "Really," or "I'm for real when I say this." Usually "Maji de?" (mah-jee day) but frequently used without de. Supposedly this is a more masculine form, but teenagers and young people of both genders favor maji, while older people use "Honto?" or "Honto ni?"
muzukashii (moo-zoo-kah-she-ee): difficult. A frequent classroom exclamation, or aside.
Muzukashii ne? (moo-zoo-kah-she-ee nay): "Difficult, isn't it?" or "It's difficult, huh?"