I'm a college student at a small liberal arts school so not many people throw parties here. Whenever I do, I inevitably see people at my house that I've never even seen or talked to, since word gets around fast and people usually have no other parties to go to. If I'm trying to make it big, I openly tell everyone in my class the occasion and that everyone's welcome to come kick it. Even kids I don't usually talk to hear it and sometimes come.
Depends on your personality and situation, but I usually tell most people to come celebrate if they want to, mainly the cute girls that I'm not too acquainted with

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A morning of awkwardness is far better than a night of loneliness.
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