This is a sound, usually used in disgust, agrivation or disbelief. It can mean a number of things, "such as screw you", "whatever", "fuck off", or "yeah right"

Mercury retrograde is the act of taking a shit whilst mooning one or more human beings. Your day can typically being going well, according to your horoscope, until you are forced into witnessing Mercury retrograde. Performing Mercury retrograde will often speed the astrological cycle forward for the individual performing the Mercury retrograde, bringing about happy and fruitful times to come.