A nettoblaster is a CD player/radio with very poor sound quality. They are closely related to the ghettoblaster but their sound quality is severely inferior and listening to it for prolonged periods of time can make you want to commit suicide.
These poor quality CD players are often referred to as 'nettoblasters' because they are thought to have been bought from the shop 'Netto'. This shop sells goods at very low prices and because of this their quality is often reduced.
Nettoblasters can be seen (and unfortunately heard) in town centres all over the world. They are often found resting on the shoulders of teenage boys who feel the need to play their music as loudly as possible, and annoy as many people as they can in the process.
Billy: 'Where's that terrible music coming from?'
Rob: 'Those chavs round the corner bought a damn nettoblaster and are terrorising the neighbourhood with it!'