The act of having a Pinecone inserted in your asshole.
Chad- "Yo dude let's take the Pinecone Plunge! Everyone bend over and relax!"
12 year olds- "The Fortnite squad has spoken, for losing us that match we are going to give you a Pinecone Plunge as punishment!."
Camper Bob- "During my hike last weekend I got tired and wanted to rest. I sat down on the side of the trail and accidentally gave myself a PineCone Plunge. It really hurt!"