A humorous phonetic spelling of the word “rubber,” used to imitate a soft or rounded pronunciation where the “r” sound is replaced with a “w.” Often used jokingly in text or conversation to mimic the way a word might sound when spoken with that pronunciation.
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.