.sǝǝɹbǝp 081 ɹoʇıuoɯ noʎ buıuɹnʇ ʇnoɥʇıʍ sıɥʇ pɐǝɹ uɐɔ noʎ ǝdoɥ ı ¿ʇɐɥʍ ɹo ʎʞɐǝɹɟ sıɥʇ sı

I didn't know one could write text upside without making it an image. I found this post from reddit. It has been tested to work with Google Talk. I haven't test it with Yahoo Messenger.

Yeah, I know, it's pretty useless besides making some pranks.