The big seal script of character Slippery (or Slip) is
The left is character Water (Post 13), the right is character Bone (Post 458). The Water means liquid, which could be oil. No matter it is oil or water, when the bone gets wet, it is slippery. There is another explanation by Su Shi - 苏轼 (Song Dynasty), one of the most famous poet in Chinese history, he thinks that the character means "The bone of water", which is ice. Of course, ice is slippery. I like the explanation .
The small seal script of the character is