Thought this was just brilliant good way to get back at someone
http://www.sevenwires.com/play/UpsideDownLetters.html
˙ɔʇǝ 'ןıɐɯ-ǝ ɹo ɹǝʇndɯoɔ ɹǝıɥʇ ɥʇıʍ ƃuoɹʍ ƃuıɥʇǝɯos ǝq ʇsnɯ ǝɹǝɥʇ ɯǝɥʇ ןןǝʇ puɐ ǝuıן ʇnoqɐ ƃuıʞןɐʇ noʎ ǝɹɐ ʇɐɥʍ 'pןo ǝɥʇ ɥʇıʍ dn ɯǝɥʇ ʇıɥ uɐɔ noʎ ˙ʇı pıp noʎ ʍoɥ ʇnoqɐ ןןɐɔ ɹo ɹǝʇʇǝן ɐ noʎ puǝs ʎǝɥʇ uǝɥʍ puɐ ƃuıɥʇǝɯos ʇnoqɐ ןıɐɯ-ǝ ʎɥʇƃuǝן ǝɔıu ɐ ǝɯos puǝs ˙spɹɐʍʞɔɐq puɐ uʍop ǝpısdn sı ʇɐɥʇ ʇxǝʇ ɐ oʇuı ʇı ʇɹǝʌuoɔ ןןıʍ ʇı puɐ 'ʍopuıʍ doʇ ǝɥʇ uı noʎ ǝʌɐɥ ʇɐɥʍ ɹo ןıɐɯ-ǝ ǝɹıʇuǝ uɐ uı ǝdʎʇ puɐ ǝʇısqǝʍ ɹoʇɹǝʌuoɔ ʇxǝʇ sıɥʇ oʇ oƃ uɐɔ noʎ ˙puıɯ sǝuoǝɯos ɥʇıʍ ssǝɯ ʎןןɐǝɹ oʇ ʇuɐʍ noʎ ɟı