Lunch Date

I bought my coworker lunch today!  It was actually a lot of fun.  We were doing an event on campus (right during lunch time), and she said that we should get lunch on the way back to our offices.  Then she remembered that she had left her wallet in her office.  We decided that we would go back to the office first and then get lunch.  

Well, when it came time to actually go, I told her I would buy her lunch.  She agreed, but only if she could reciprocate next week, which I accepted.  Technically I benefit from this by getting lunch next week; however, when I made the offer I had no expectation or desire for reciprocation.  I only accepted because I knew that was the only way she would let me buy her lunch today.