An unkempt, unhygienic, malodorous, greasy, sludgy vagina. Chumbucket may also refer to a female with such a vagina, who is often an overweight and/or unsightly slob of a woman, often with the appearance of being pregnant. A chumbucket is known to secrete chum.
I can't believe he stuck it in that chumbucket... and she left a stain on the carpet.
a person who is such a slut that they can be metaphorically represented as follows: as being a bucket which collects the ejaculate of thousands of soldiers who have not seen their wives/girlfriends for years. If every soldier (amongst thousands) was ordered to ejaculate into a bucket, this bucket would represent that slut.