An employee who sexually harassed colleagues and told his bosses to f--- off at a Christmas party was unfairly sacked partly because the company had supplied him with a free flow of alcohol, the Fair Work Commission has found.

Employers may not be in a position to insist on standards of conduct at functions if they serve unlimited amounts of free alcohol, the commission found.

At the Christmas party the employee told a company director and a senior project manager to "f--- off". Credit:Michelle Mossop

It heard a male employee at Leighton Boral Amey Joint Venture had about 10 beers and one vodka and coke, including two stubbies before he arrived. At the Christmas party he told a company director and a senior project manager to "f--- off". He asked a colleague "who the f--- are you? What do you even do here?"

After the party had ended, he joined some colleagues at a public bar and called one a "stuck-up bitch" and kissed another.