You take a look at the page in the myth book, and notice a picture of a creature that had the head, arms, and torso of a woman, while the rest of her body ended up in a long green tail. "What's this one?" You ask, as you turn the book over to show your girlfriend. "That's a lamia," your girlfriend says. "Very sexy creature."
"Well can you transform into that?" You ask. "Sure," your girlfriend answers, then blinks to reveal yellow snake eyes in her iris's, while her tongue became skinnier, and 2 of her teeth become sharp. Net, large green scales grow on her legs, as they extend, they fuse together, and the bones start melting. What was left of your girlfriend's legs became a long scaly green snake tail that was long enough to go through every room in the house.
Your girlfriend then used her snake tail to wrap around you, and pulls you closer to you. "Caught in my sssexxxy trap you are," your girlfriend explains. "Makesss me hungry." Suddenly those words start to make you shiver.