I'd say there are 4 different stereotypes of penn students, depending on which school you're in; Wharton, the College, Engineering, or Nursing. "Whartonites" are known as the cut-throat profit driven, win at all costs type of people. They're the ones setting the curves, going to office hours, and fighting for every last point on every exam. In the college of arts and sciences, we're more laid back, well rounded students. Often indecisive, and prone to complain about class, while staying up til 4 a.m. in van pelt to finish off the 15 page paper due tomorrow. Penn is known as the "social ivy", and students in the college have no problem living up to that name. It's not unusual to see students out at parties as early as thursday night. Engineering students pretty much don't exist outside of the engineering buildings. Their work ethic is different than Wharton students, in that it's not so competitive or money driven, as it is just genuine interest in learning the material, and passing with an A+. Consequently, between 7 class schedules and back to back to back all nighters, engineers pretty much stick to themselves. Nursing students are the soft, nice people who always say hi, and never seem to be too stressed about anything. They seem to live laid back lives, only ever complaining about 7 a.m. clinicals. While of course not every person in these respective schools is a member of these stereotypes, on the whole, they seem to be pretty accurate in capturing the personality of the schools. Thats perhaps why one of the first questions a penn student asks another penn student after first meeting is, "which school are you in?"
I think most stereotypes, if any, that you'll find at a school like UPenn exists primarily within the Greek community. There are certain fraternities and sororities that have developed reputations and seem to recruit students who fit that mold. For example, Delta Upsilon is often cited as the fraternity with the highest collective GPA on campus, recruiting ITAs (Information Technology Advisors) and Asian nerds. While this may not always be true, there seems to be a "type" of person that typically joins this fraternity. Futhermore, aside from stereotypes, UPenn is organized according to social circles. These circles are developed by people who all share a common interest. Whether its the Penn Democrats or the Latino Coalition, there is a support group for all types of people and a good chance that you'll meet someone just like you. Each circle elects its own leaders and these individuals act as representatives of these communities to higher university officials. This does not mean you are automatically placed within a specific group of people, however. It is very easy to navigate across social environments. There is room for everyone and anyone.
Stereotypes at Penn are similar to most about Ivy League schools--rich, spoiled, preppy white kids. Certainly there are some people like that, but the vast majority are not like that at all. Penn is a diverse school both ethnically and economically, though there is naturally room for improvement. Most of all the students are highly intelligent and motivated, though the Wharton (business) school students are perhaps more competitive than most others. Overall the university is big enough to attract many different types of people and most students should not have trouble finding a niche to occupy comfortably.
I think one common stereotype about Penn is that it doesn't have much of a campus. Compared to other rural and suburban schools, that's probably true. However, being a city school, Penn has a pretty impressive campus. Locust Walk is beautiful in all seasons and it's essentially only accessible by foot so you don't have the disruption of city traffic. And all of this is in the awesome city of Philadelphia, so you have advantages from both the campus and the city.
People think that students who attend the University of Pennsylvania are more academically oriented, more competitive, and more presumptuous than the typical college student. Also, there is the notion of our being the party Ivy. Although it is true that students care about studying, there're many other causes and activities to which everyone dedicates their time. As for socializing, there's a healthy does of that.
The student body is really diverse so it's hard to pin down a stereotype of all students when I think about UPenn. There are a lot of Jews, if anything, and Asians, but you can't tell apart the frat boys from the nerds because we're all nerds.
Academic; smart workers and hard players.
The typical Penn kid usually lives a double life. They work hard during the day and week, but make time to go out Thursday, Friday and Saturday nights...sometimes even more. Most Penn kids are pre-professional. You have the whartonites looking into consulting and IB, the pre-meds, engineers and lawyers. The great thing about Penn students though, is that despite being highly academically and professionally driven, they are passionate about many things. Penn is great for diversity. Only here would you find an Asian Computer Science major that is in the campus Hip Hop dance team.
People tend to think that Penn has a lot of rich, snobby white folks. Though there are a number on campus, the majority of students are very nice. Penn is also considered the "social ivy" and that is definitely true. Everyone works hard, but they definitely know how to go out and have fun at the same time.
The stereotype is that Wharton students are competitive and cutthroat, the Nursing kids have it too easy, the College of Arts and Sciences Kids are too lax, and the engineering kids have it rough and have no lives.