Most tend to save this insult for when they are against a opponent of the chav nature. Recent tests have proven that the more burberry the chav is wearing, the longer time period it takes for the insult to sink in.
WARNING- when using the Id Face attack, always use against people of IQ level under 50, oh and don't throw into an open fire.
BERT: f**kin' chav
CHAV: Hey mate, your mum
BERT: Shutup, you ID FACE!!!!