Kimbo Slice to Ken Shamrock -- 'I'm Gonna Break Your Jaw!'

MMA star Kimbo Slice doesn't just want to beat down Ken Shamrock -- he wants to BREAK HIS FACE ... telling TMZ Sports, "To end his career, that sounds pretty good to me."

41-year-old Kimbo and 51-year-old Shamrock are scheduled to do battle at Bellator 138 in June -- and Slice says he won't be satisfied unless he actually SHATTERS several of his opponents bones.

"I'm gonna break his ribs and break his jaw."

In fact, Slice says he's willing to fight BARE KNUCKLE -- because he really wants to inflict as much damage as possible.