This is a very, very common thing amongst Irish people when describing a person, place or thing. Because sometimes we can't articulate how large or small an object is, or the skin tone of an individual or even the heat of a local curry dish - we use this a lot! We basically just say the word twice and the person who gets the info knows exactly what we mean by tone alone.
A different word for up, used for supporting teams/people/etc. usually with the word 'the' afterwards if it's somebody's name. Examples: "Scup the (person's name)!", "Scup Louth!"