This kanji is usually only seen by itself in fortune-telling. It's like the worst fortune or whatever, so it's frequently the punchline of jokes.
In May, I fell into a terrible pit and I am still trapped there until TODAY (今日, pronounced KYOU)!!
凶 (terrible) + 悪 (bad)
= 凶悪 ( Heinous!)
atrocious! Heinous! Some Rape of Nanking kind of shit.
大 (big) + 凶 (terrible)
= 大凶 (horrible luck)
horrible luck, an atrocity.