Firing an employee with bad manners may be lawful or not. It depends on the status of the employee. If he is on a probationary period, he could be fired on the spot. The case must also depend on the cause of firing the employee. If the reason is his bad manners, the company might be the cause of having such attitude, however, as a probationary, you need to be cautious of your actions because your credentials show no holding power for your retention at work. The employee might have refused to do his task willingly and instead of doing it, he assigned his co-worker to do it for him which is impractical. If the employee is a regular full -time and fired on the spot, it will be illegal. That employee may seek a lawyer but if his conduct is unlawful, he may face a trial, the best option is to resign.