To get stabbed, sliced, chopped (to bits, obviously), slashed or otherwise involuntarily come into contact with the business end of an edged tool (e.g. a knife, ax, katana, razor blade etc.) to the point of being rendered no longer a nuisance or, ya know, alive.
Stemmed from the Spyderco Lum folding knife designed by Bob Lum, and the British slang term "lumped up."