Silence of the Lambs - Dying Light Easter Egg
You can find the Silence of the Lambs Easter Egg inside of the same building where you fought the kidnapper for the "Where's My Mother?" Side Quest. This building is found in the northeastern portion of the Slums, due north of the Fisherman's Village.
When you drop down into the basement search the bookshelf to your right, you'll find the lotion in a basket.