Troma is the one of my favorite film production companies and all their movies are terribly wrong. (Independent for more than 30 years)
One of the craziest of them all is:
TERROR FIRMER:
A homicidal maniac is on the loose in the city and the low budget film crew on a Troma movie have the power to stop them.
Some reviewers have said that it contains too much "trash" and related elements, and may be excessive in that regard

PINK FLAMINGOS:
Of course the man John Waters has been doing it wrong for years:
-A family of rednecks and a pair of swingers do battle with one another for the rights to the title "The Filthiest People Alive."


The ones above are nasty but humorous.
As far as rough and brutal, all the Takeshi Miike films listed prior are good but if you haven't seen his contribution to the Masters of Horror series, entitled "Imprint", check it out.
IMPRINT:
Imprint is the installment in Showtime's "Masters of Horror" series famous for not being aired in the US
