Secret Passageways Recorded in Leonardo da Vinci's Sketches Discovered Beneath a Medieval Castle in Milan
Just a moment...
I am a simple man. I see GPR; I upvote.
You're a penetration enthusiast?
Haha, yep. In grad school my wingman would introduce me at the student pub like this:
Wingman: "This is my buddy Troy. He studies penetration."
"Oh really? How deep do you penetrate?"
Me, as straightfaced as possible: "Depends on the frequency, but usually a few metres."
Didn't work as well as offering to show them my six inch telescope (and then taking them moongazing), but still hilarious.
Haha!