What are you feeling guilty about at the moment?
I am feeling guilty because my colleague, who I like very much, has had her request for holiday refused because I have already booked that week. Usually this would be minor guilt, but to rub it in, she wants that week because it's her birthday that week, and her boyfriend has already booked the week off from his job because they planned to go away. I'd change, but I've already booked my holiday (to Scotland, FYI).
She sent me a jovial email that hid an undercurrent of pure rage.
I feel terrible.