short, sharp shock

1 a brief but harsh custodial sentence imposed on offenders in an attempt to discourage them from committing further offences.

2 a severe measure taken in order to effect quick results.

☞ The Home Secretary William Whitelaw advocated the short sharp shock as a form of corrective treatment for young offenders at the 1979 Conservative Party Conference; the deterrent value of such a regime was to be its severity rather than the length of time served.