how had you done to remove head with axe? (task 26)

I'm sitting knocking out all the achievements and I can't get a fatality about block B5, who knows how to do it?

I have 30 out of 31 hats, and cannot figure out how to get the last one. I'm missing the 5th hat (top row, 5th from left). I have completed every challenge, done each type of fatality at least 3 times (including both lasers), earned every Steam achievement (eff that stupid desert bird, by the way), got a max score in the sandbox, etc. Anyone have any idea of something else I could try?...

Let's figure out who has ♥♥♥♥♥♥ the highest in the desert. I've ♥♥♥♥♥♥ 460.9 meters.

Honestly found this really confusing, any one able to help?