OMGraham is a term of expression used when one is struck by the dreaminess of a tall, handsome, South African gentleman. It is also synonymous with OMG(osh)/OMG(od).
Similar to OMG (Oh my god!), but ending with a fashionable "osh" to imply "Oh my gosh!", which isn't "Oh my god!", which is important, if importance was the issue. Which it's not.