Maybe a KIDNEY.
You already have his testicles.
The Big Bang Theory Season 11, Episode 9
Do you remember those KIDNEY pies
Old Nan used to make?
Game of Thrones Season 6, Episode 4
Kidney? Cornea? Piece of his liver?
The Big Bang Theory Season 8, Episode 20
...oyster, KIDNEY bean and grape.
The Big Bang Theory Season 3, Episode 17
You wanna see
James Cameron's KIDNEY stone?
The Big Bang Theory Season 8, Episode 7