- The "sorority girls" just gain weight if you buy their cookies
- Parts of the sandwich can be given to characters to unlock their final stage basically. Most of them end at a somewhat realistic weight, the sandwich raises it to straight up cartoonish. Hold off on giving anyone the whole sandwich though, since you can't use it anymore after that (it unlocks some truly huge weight levels though)
- There's not a true ending in that sense, just a sort of end point when you reach a certain weight. Depending on which partner you choose to stay with, the last weight stage epilogue varies. Apart from that, the "bad endings" you can run into during the process of getting there, are little dead ends that are non-canon, but can show some fun scenarios.