Spiderman's Semen Killed Mary Jane!

From Spider Man: Reign #3:

Oh God, I'm sorry! The doctors didn't understand how it happened! How you had been poisoned by radioactivity! How your body slowly became riddled with cancer! I did. I was... I am filled with radioactive blood. And not just blood. Every fluid. Touching me... loving me... Loving me killed you!"

Sadly, this is not a joke.