You were the class mom, you were kind, you didn't judge people for how they looked or acted, you took the entire class shopping (or to McDonald's), you made everyone cookies and helped anyone.

One night, you were studying. You were tired, you haven't had a break and it was breaking you! Everyone knew this, and they felt terrible, for all the things you've done for them, they haven't had a chance to re-pay you.

So,

They were going to get you gifts, they were going to suprise you. The plan was: They get gifts, decorate the common room, and write a letter and leave it in the middle for you to read and hide, wait for you to come down to read the letter before jumping out to suprise you!