Nonsense, rubbish.

This is a classic of Cockney rhyming slang. It originates from cobbler's awls, which are the pointed hand-tools that cobblers use to pierce holes in leather. The rhyme is with balls, or testicles.

The phrase is often reduced just to cobblers, which is now considered an acceptable vulgarism, as many may not be aware of its origin.

See also, other phrases that mean rubbish or nonsense: