Ruse (noun)– a trick or act that is used to fool someone
A colleague of mine is getting married over spring break. Our department chair sent out an email letting the rest of us know about a quick surprise celebration for her during a free block. “The ruse will be to discuss Term 2 grades, but I’ll tell you now in this email.” He then continued on to explain how to calculate year-to-date and term grades. Under the impression that we were having a last-minute department meeting, she was surprised to find that we got together to congratulate her on getting married.