When something sounds very unclear/unrecognizable to the ear. Something about whatever you are hearing just isn't quite right!
DD: I wouldn't recommend listening to your drums and your ipod through the same speaker, you should split them up into different channels, if not, it will sound real "Marbled Up"!
Longo:Those chicks want us to pick them up tonight but they live 50 minutes away:
GD: F,, that, that plan sounds "Marbled Up"!