My Chinglish is getting pretty bad. I've noticed that when I skype with people back home, I'll accidentally use Chinese words in my conversations. It's hard not to though--there's a lot of words that we use here (in Chinese) that don't necessarily have a good English translation, or one that we want to use: we don't say "homeroom teacher" because that's not what that person is, "Chinese barbecue" isn't shaokao, "redo class" just sounds weird, and saying "county city" seems unnatural. There's also a huge realm of food words that we use the Chinese for mostly because we would have no idea how to say it in English. There are fruits, vegetables, animal parts, and dishes that I only know the Chinese for.
The Chinese fellows also use English for a terms that we learned over summer-institute because there's often not a great Chinese translation of the same concept, or the translation sounds silly. Our Chinese fellows also tend to express their displeasure (&!*# etc) in English as well because nobody understands English other than us.