What's the past tense of blew?
It's already past tense.
What's the past tense of blue?
Blued. As in metal.
You're thinking of blow, faggot.
Cobalt-60
Something something North Korea has a stockpile of something cobalt related that when exploded lets of world ending amounts of gamma radiation inside the atmosphere.
https://en.wikipedia.org/wiki/Cobalt-60