Wide Eyed Spankee
To my mind, there’s nothing to match the expression on a girl’s face when she discovers (or, more commonly, remembers after too long without) that spanking actually hurts:
From Clare Fonda Pass.
Spanking Blog: Adult Erotic Spanking At Its Best
 |  |  |  |  |
The first swat is always the attention getter, esp as she realizes the it’s just the first of many more to com!.