Martyrs isn't exactly disgusting or shocking but it's extremely intense- visceral and disturbing. I felt strange for days after watching it.
If you're looking for something 'extreme' to watch I'd recommend it, I think it's the most unsettling film i've ever seen.
Ichi the Killer and Tokyo Gore Police are good if you're looking for things with buckets of gore and striking imagery, but both are too cartoony and fun to be described as shocking. The most disgusting part in Ichi is the title rising out of spunk at the start. Semen/lymphy stuff is waaay more disgusting than blood