@moollaza a bit scared that "normal" might appear somewhere else in the string.

http://a0.twimg.com/profile_images/1873652107/128_chrome_radius_bigger.png
http://a0.twimg.com/profile_images/3375649973/82c8b3dba07cebb44751ebcaaf3ecd5f_bigger.jpeg
http://a0.twimg.com/profile_images/506027586/twitterpic_bigger.jpg

I guess it can be simplified to `image.replace(/_normal\./, "_bigger.");`