I had a major case of senioritis, but that had nothing to do with college acceptance. It had to do with the fact that as I began my senior year I only needed two classes to graduate (English and Gov't/Econ), and I'd signed up for a big class load anyway involving Calculus and AP Physics. Both of the latter two were taught by the same teacher who wasn't actually interested in teaching anything or earning his living, so I ended up dropping both classes, found myself with little else worth doing for the school day, and decided to skip school a lot... like 15 absences per class per semester.
And I still pulled straight As.