But I don't wanna wear a dress!

Ok, so nobody is actually asking me to wear a dress, but they do want me to "dress-up." My definition of "dressing-up" is anything more than jeans and a t-shirt or tank top. That includes, polo shirts, button-ups, anything with a collar, anything fitted....etc. See, part of the reason I am so attracted to LAB jobs is that you can wear jeans, t-shirt, and lab coat....and nobody can tell the difference! I also understand that sometimes you SHOULD "dress-up." Like when you're going to church, a wedding, a funeral (usually), special events (concerts, plays, art shows), or when you need to make an impression (at professional meetings, seminars, presentations). Generally, my everyday existance doesn't include any of these. Maybe once every 2 months I may have to participate in something, but I try not to make a habit of it. Some people, though, feel like they HAVE TO dress like this EVERY DAY, or maybe they just LIKE it! That's great for them, but not for ME. So, this summer I am participating in a Graduate Program and our "Etiquette Guidelines" state that we should "be dressed in clean and tidy clothes that present a well put-together appearance. Revealing clothes including tank tops and baggy low-riding pants should be avoided." I guess that's clear as far as tank tops go, but what about t-shirts? I have some "nice" shirts with "neutral" screenprints on them. So, I asked. And I was told that I should dress as if I was prepared to meet someone. You know the cliche about first impressions. But, the job that I plan to have one day does not require this kind of dress code. So, what kind of impression do I need to make? I think it's like putting false information on your resume: I'm giving the impression that I normally dress like this. So, if the person I meet were to hire me, they would expect that from me all the time, right?
I guess I've gotten spoiled at all my past jobs. Only 2 required a uniform (fast food & toy store), while all the others (animal shelter, animal rescue, girl scout camp, lab assistant x2) allowed the employees to wear "whatever" as long as there is nothing offensive.
So now I have to go shopping to buy some "nice" shirts (I'm not giving up my jeans). Hopefully Wally World will have some cheap ones?! In the few days since the program began, I have already exhausted my "nice" wardrobe :)
Aaarrrrgggghhhh!