What do about a hickey?

i came to school with a hickey and my English teacher saw it and just sighed at me. for the rest of the period she was kind of mean in a teacher way and shes usually really nice to me. why did she do this(shes in her late 20s or early 30s) and really hot lol? how do i make it go away really fast without leaving a scar? and im 16 if that helps