Lean Tuna And Her Stepbrother’s Plan To Become A Fatty Tuna summary: “You, you’re too bad at s.e.x!” When he was finally caught cheating, my boyfriend verbally abused me by saying that I was terrible at s.e.x and called me a dead lay just like a frozen lean tuna. I will become skillful at s.e.x just like a fatty tuna woman, make him speechless and declare it himself. Involving her younger stepbrother, the air-headed lean tuna’s challenge has began.