Misconduct is an “improper behavior, intentional wrong-doing or deliberate violation of a rule or standard of behavior…Any conduct inconsistent with the faithful discharged of his duties” [Holiday Inn Kuching v Elizabeth CS Lee Award No. 255 of 1990]. It is also An act or conduct that adversely affects employees duties towards the employer. The misconduct complained of must have some relation with employees duties or the work entrusted to him by the employer. Any breach of an express or implied duty on the part of an employee, unless it be of trifling nature would amount to a misconduct [Sykt. Kenderaan Kelantan Berhad v Rosidi bin Zakaria Award No 542/1995].

Syed Ahmad Idid (1997) listed acts of misconduct lead to penalty of dismissal:

Prejudicial or likely to be prejudicial to the interest of the master;
Inconsistent and incompatible with employee’s duty to master;
Unsafe conduct for the employer to retain the employee in service;
Immoral conduct acknowledged by reasonable persons;
Unfaithful conduct which make it difficult for master to rely on;
Not properly discharging duties properly;
Abusive or disturbing the peace at workplace;
Insulting or insubordinate behaviour between employer and employee;
Negligence of duties which is engaged; and
Act of neglect tends to cause serious consequences

Acts treated as misconduct:

Disobedience;
Theft, fraud;
Willful damage or loss of employer’s goods;
Habitual absence;
Habitual late attendance;
Drunkenness, fighting;
Sleeping during working hours;
Habitual negligence;
Smoking in prohibited areas;
Failure to follow safety rules;
Sexual Harassment;
Resorting to industrial action in contravention of the provisions of the Industrial Relation Act or other laws.

For more information and soem details about dismissal procedure you can check here.