Meaning

adjective earthy and sexually explicit

adjective suggestive of or tending to moral looseness

adjective thickly covered with ingrained dirt or soot

originOf unknown etymology. Originally U.S. Army Air Corps slang; origins among cadets in Texas suggest a possible connection to Mexican Spanish rancho (see ranch), which had connotations of animal filth by 1864.

Etymology from Wiktionary, CC BY-SA 3.0