Slug Lady appears in "Slow Love" as Snorlock's mate. She pretended to be a snail, but confessed that her shell was actually a peppermint (or at least, made of it). At the end of the episode, she and Snorlock make out, much to Finn and Jake's disgust. It is unknown why she pretended to be a snail, but it was probably to find a mate, which was Snorlock's motive.
Slug Lady looks like a giant slug, with slightly lighter lime green skin than Snorlock. She has two green ribbons at the root of her eyestalks. She has longer eyelashes at the top of her eyestalks, which is interesting in that none of the Snail Ladies had eyelashes.
Actually, I'm not really a snail. I'm a slug. *shell falls off* My shell is made of peppermint.