An amalgamation of the words 'shit' and 'lad'. Used to convey dissatisfaction at the actions of a certain individual. Can also be used as a general greeting. In the case where these actions are undefendable, the choice words are 'massive shlad'.
Also see 'shladding it up', the act of being a shlad while doing an undefined activity. This can include choosing work over a night out or relentless visits to the fitness and gym facilities.