With our final project we've been told to ask questions and get a deeper understanding of why something is the way it is. So you could maybe look at why lyrics have meaning to them, and how changing one word in a line from a song can dramatically change the power or the meaning behind the whole thing.
If we take the example above, would the line "I see a red door and I want to paint it green" have the same edge to it? What is it about the colour black that gives the lyric its' strength? The connotations of black and how we use it in a dark way perhaps?
Similarly you could change words to others that sound the same but have different meanings, and so change the whole concept behind a song. For example, in The Smiths song "How Soon is Now?" Morrissey sings the line "I am the son, and the heir", but this could be mis-interpreted as "I am the son, and the air", which obviously gives the song a whole new meaning.
FMP's (or the ones for my course at least) are very heavy on theory and development. We're told not to go into them with an idea for a final outcome, but have an idea that you can explore and experiment within to eventually come up with something that's driven by a deeper understanding.