Hip-hop records tend to contain a lot of swearing. So, for radio play and pre-watershed television, they blank the offending words out. Fair enough.
Then some bright spark finally realised that these records with every third word missing just sounded like the rapper had a rather odd stutter, or perhaps hiccups, and they started filling in the gaps. Eminem decided to use a DJ to scratch-mix in distorted and unrecognisable recordings of the offending lyrics. This is pretty cool.
Then The Pussycat Dolls had the inspired idea of beeping out words, but using a really loud and in-tune beep and making it an integral part of the music. This is very cool indeed.
And now there's Lily Allen, taking it to the next step. She has obscured the "offending" words in her new record, Alfie, with comedy brass fills. So, for instance,
My little brother's in his bedroom smoking weed
My little brother's in his bedroom smoking [Parp! Wooooooop! Honk honk!]
(Because "weed" is a very, very offensive word, you see.)
Ms Allen must be the only person ever to have responded to the spectacle of one clown pouring whitewash into another's trousers while the trombone plays "Wah... wah... wah... waaaaaaaaaaah!" by thinking "What fantastic music. I must try and incorporate that into a hit record."