Although I thought it was cool when I first came to Japan (partially because I was so excited about studying the language), I would really like to change my username.
My best friend used to make fun of me for wanting to go to Japan, and at the same time, he also used to make fun of me for dating multiple girls at once. So, he used to call me a 'pimp'. And it just naturally progressed to Japanese pimp after I decided to go to Japan way back at the end of 2001.
The word for Japan in Japanese can be pronounced either nihon or nippon. The word for pimp in Japanese is pronounced ponbiki. 'Japanese pimp' in Japanese would actually be 'nippon no ponbiki', but as a play on words and so no Japanese person would likely figure it out, I shortened it to 'nipponbiki'.