This is a derogatory term used to refer to a women of large proportions, an exclamation as they pass by, or a code word while making fun of them. It derives from the aforementioned's love of ranch dressing. A love so deep that they maydrink ranch straight from the bottle.
"Oh here comes Carla... quiet, quiet, she's walking by........ Raaaaaaaaaanch!"
Used to express feelings of anger, frustration, fatigue, hunger, or any other emotions that are unwanted; frequently related to the roar of a Lion (although more frequently related to the sound of a strong yawn).