Workin at McDonalds isn't as bad as everyone thinks (worked there for over 2 yrs and gone through the hating it and loving it stages), the hours are pretty felxible and you can book days off as you wish due to the nature of the system (obviously you can't abuse it or they say something).
The one I worked in thru 6th form and during uni holidays is pretty quiet so it can be dull but it depends on the people working there (mostly students in those holidays).
Oh and you don't smell as bad post shift as you'd think, well not when you run drive thru most of the time like I do (kitchen staff obviously get it worst)
Negatives are the managers can be very demanding of when they want you to work, they don't care one bit if its outside your availability or you have 5 exams the next week.