IT'S 8pm, you rub your neck in a useless attempt to unwind the growing tension knot and your eye twitches as you stare at the computer, trying to desperately finish that dreaded report so you can get home in time to kiss the kids goodnight.

You've been in the office since 7am and you know when you do finally get home your partner will be angry with you working over again and there'll be that inevitable argument about how you're married to the job.

Sound familiar? Well, today's your chance to get your own back against your tyrant boss who keeps you chained to your desk all hours of the day and night.

For employees working unpaid extra hours can send their manager an anonymous boss-a-gram, suggesting that he or she should show some gratitude for their unpaid overtime on today's Work Your Proper Hours day.

Hacked off employees can log on to the Trades Union Congress's website www.workyourproperhoursday.com to anonymously submit their manager's e-mail address and they will be sent a message, saying: "Hello boss! Someone in your team has asked us to let you know that it's Work Your Proper Hours Day today.

"February 25 is on average the first day that people who do unpaid overtime would get paid if they did all their extra hours at the start of the year.

"It's an opportunity for every manager to say thank you to their staff for their hard work and commitment, and maybe even buy them a drink after leaving work at the proper time for once.

"And if it's any consolation, managers do even more hours. So you deserve a break too!"

The message may be tongue-in-cheek, but the issue is certainly not something that should be sneered at, says Alan Weaver, Worcestershire spokesman for TUC.

He said shocking figures reveal that 391,000 West Midlanders work unpaid overtime, losing out on an average £4,400 extra pay a year - a total £1.7bn per annum.

"I think employers take advantage of their workforce because they know people want to do a good job so do the extra time no questions asked," said Mr Weaver.

"No lunch breaks, the odd half hour here and there and they really add up. It's about time employers recognise what they are doing.

"It not only means people are losing out financially, but it also has a massive impact on their social and home lives.

"And it's questionable whether people can work effectively and efficiently if they're doing so much overtime.

"Good businesses will recognise that this is a serious issue and would not want to work their staff into the ground.

"If you do the overtime it should be recognised and paid for."

And if you think your manager is evil, spare them some sympathy, said Mr Weaver.

"Managers are actually the worst hit and lose out on about £9,000 a year in unpaid overtime," he said.

As well as sending a boss-a-gram at the TUC special website, you can:

n Check out how much your own unpaid overtime is worth

n Download an unpaid overtime calculator to send to your friends by e-mail

n Order or download posters for the office

n Find out about special deals for staff who want to leave work on time and celebrate the day, preferably with your boss picking up the tab.