Blocks
Common SlabWide Expletive.
Used to express dismay, frustration or nonsense.
Examples in common usage
That's a load of blocks! Oh blocks! He's talking blocks!
Derivation
Most people believe it is exactly as it sounds, i.e. describing a negative block or hurdle that has become a restriction or barrier to progress.
However this belief is, in itself, blocks. The word is a contraction.