Someone that is crazy or acting irrationally. Also used for someone negatively outspoken and loudmouthed. Mostly used by the yorubas in Nigeria,West Africa to define madness.
A person whose reasoning is off the roof, who see things from an expected angles and do things with some degree of genius. (Whereas is not a genius of any sort)
A sunburn or suntan focused on the left arm. It is caused by the left side of the body being the only half that gets exposed to sunlight while driving. Presumably, it would be located on the right side of the body in countries where they drive on the left side of the road.
British slang for a scientist or technical expert, esp . when the speaker is not certain of the expert’s specific field of study. Not necessarily derogatory, but typically used by persons without a technical background. In the US, the equivalent would be “egghead”, “squint”, or “geek.”
Origin of the word is unknown. Started sometime in World War 2. Given the typical evolution of British slang, could easily have started because what these experts did was confusing or “baffling” to the common person.