The act of fingering a girl, which her insides feel like a warm lubed piece of bubble wrap, hence apple pie].
"Me and Fernie-Bitch went at it for hours. I love apple pie-ing her."
"I totally apple pied Angie last night while her mom recorded everything. It was the best night of my life!" she exclaimed.
"oh man...it smells like someone was raw apple pie-ing an old pussy."