I hate Casual Fridays.
Here is why - some people take it way too far. A t-shirt might be ok, but an Iron Maiden concert shirt? Sneakers might be ok, but flip-flops? Work-out clothes? Seriously, it is still work & not a vacation.
Dress with some professionalism just in case the vice president decides to descend into your office or an important client arrives at reception. Even in a casual work atmosphere, there are limits to what is acceptable.
Click here for a good article in the Workopolis Career Resource library about your work image.