What are the expectations at work Christmas parties?

Ready or not, the Christmas party season is fast approaching and the work knees up is often where you find out who's naughty and who is nice. But no one wants the hangover of an HR investigation so it's best to get a clear idea of what is expected at the end of year shindig. In all seriousness, the work Christmas party can be quite problematic for both workers and employers. Money correspondent Susan Edmunds spoke to Lisa Owen.