!clear limpia el chat en justin.tv puedes cambiar por el que quieras
borradoooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo
Tidum i guess that on Justin.tv has a different command to clear it, cause there is other snippet here, that another guy used /msg $chan /clear like this one
http://www.hawkee.com/snippet/8016/
i never used it, so i dont know how it works