Panty Shot
A specific variety of Fan Service, the Panty Shot is exactly what it sounds like: a gratuitous exposure of a female character's panties.
This form of Fanservice tends to be uncomfortable (and incomprehensible) to the poor souls accustomed to underwear exposition of the "I See London" variety. Often averted by using a Magic Skirt or Modesty Shorts.
When this is Played for Laughs, it's Comedic Underwear Exposure.
No examples, please; this trope approaches People Sit on Chairs territory in the works where it would make sense to have it at all