Is there any nice way to stop the students from sticking with bad english names?

I'll admit to thinking Eleven is a good name.  Also, Seven.  I don't know why.  Perhaps because they're a little bit creative, yet have no weird background nuances in English.

I've had at least a dozen girls named Seven. The best one was no better than a 5.5.

I still like "Hi, I'm Kinky"
Cool, we'll talk after class but for now just tell me your name   

The number 7 (七, Pinyin: qī) symbolizes "togetherness". It is a lucky number for relationships. It is also recognized as the luckiest number in the West, and is one of the rare numbers that is great in both Chinese and many Western cultures. It is a lucky number in Chinese culture, because it sounds alike to the Chinese character 起 (Pinyin: qi3) meaning arise.

If its any consolation...they tend to ditch them when they 'enter society'. I normally have adult students and donwright silly names are rare in adulthood.