as hell = in an extreme way

as hell は （形容詞）+ as hell のように使われます。1:58 it's intimidating as hell. クリント・イーストウッド監督は俺たち役者を馬のように（優しく）扱うのさ。大声でアクションと叫ぶと馬がビックリするので、ドスの利いた声でじゃ始めろとかもういいとか言うので、余計にビビってしまうのさ。

Tom Hanks' Amazing Clint Eastwood Impression - The Graham Norton Show

https://www.youtube.com/watch?v=q4_Be8HJe9o  0:02 they are mad as hell and they are not going to take it anymore.
Occupy wall street anger

https://www.youtube.com/watch?v=0Nq7Qe4PJVA  3:27 the only way that people could send a real message that they were mad as hell and they weren't going to take it anymore was by voting for Donald Trump.　
Making America Great Again will be much harder than voters think

https://www.youtube.com/watch?v=X8YUkwjAdOw  2:04 I'm mad as hell and I'm not taking it anymore.
Erin Brochovich Fights On