Based on experience in college, I'd have to say chemical engineers. I've never met one who can be described as sane.
In my workplace we only have mechanical, materials, electrical, and software engineers. Based on that pool, I'd have to call our small materials engineering crew the kooky ones. I do a lot of work in the materials lab and the kid who's the "lab supervisor" is a true mad scientist. Every time I go down there he's either playing with the SEM or experimenting on something else under the fume hood.