I have to purposely and willfully shoot myself in the head of my own volition with no outside influence or someone trying to force me to.
That two people that don't know each other that happen to have the same name stab me directly in the heart with a blade made of bone one second after midnight on Friday the 13th while saying my name backwards. Even if it happened I would be super impressed and accept it.
Crushed by a 650 lb albino woman named Zacharia on the third thursday of a 31 day month during a leap year while a choir of octogenarians do a cover of Weird Al's greatest hits.
Being killed by Ultron is impossible. Ultron is a character from a comic book. Comic book characters can't kill you.
Being killed by a black hole is possible, though the probability is incredibly tiny for a few billion years.