The pairing name for the two main characters of the Halo series, the Master Chief and his A.I partner, Cortana. "Green and Blue" is also the name of a track in the Halo 4 Original Soundtrack.
**Spoilers**
The song plays at the end of the Halo 4 Campaign, where the Master Chief is seen in a blue bubble-like hardlight shield, and is confronted by Cortana, only to be told that she cannot accompany him away from The Composer, as the physical remains of her is down at the site of the debris from The Composer.
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.