The adj insane has 2 senses (first 2 from tagged texts)
1. (11) insane -- (afflicted with or characteristic of mental derangement; "was declared insane"; "insane laughter")
2. (1) harebrained, insane, mad -- (very foolish; "harebrained ideas"; "took insane risks behind the wheel"; "a completely mad scheme to build a bridge between two mountains")