Essentially, it allows people to rearrange other's days at their on whim and fancy for no good reason other than a decision to take a day off.
It is particularly useful for putting off new members of staff from partaking a meeting one deems to be dull.
M: "You would if your time management was better."
S: "I suppose you're going to tell me you have an 'opportunity' for me now aren't you?"
M: "Damn right I am!"