When an employee takes a dump once per his or her shift. Generally taking place around the same timeframe each shift. In most situations a shiftly shit is strategically planned during undesirable work situations. Such situations include eluding a meeting or to get away from undesirable fellow employees.
It was 2:30 and Jane knew bastard boss Tom would be stopping by work at any moment. Wanting to escape any possible conversation with Tom the boss, Jane planned her shiftly shit for the day.