Undergraduate students at most US colleges and universities can, and do, wear pajamas to class. The exceptions would be the very few with dress codes that require uniforms (such as military academies) or those with a strong religious affiliation. I had a nice conversation with a homeless person in NYC. It turns out that his monthly routine was to get very drunk and wasted each month, at which point he would be checked into a mental hospital to sober out. Once he sobered out and was past the mandatory hold period, then was back on the street. He was very knowledgeable as to which hospital you want to get checked into (i.e. which hospital has the nicest food and friendliest staff), of the mental health laws of the state of New York, and what to drink for maximum intoxication for minimum cost. One tip that he had was that he tried to time his stays in the mental hospitals at the end of the month, and get out before the 1st. The trouble is that on the 1st, welfare checks arrive, people use it to buy drugs, at which point the hospitals get flooded and unpleasant, since you are dealing with unpleasant people and staff that are in a bad mood.
The streets are dangerous, and you need the police to keep you safe, so you try your best to be law-abiding and do not cause problems. As long as you are harmless, the cops are very sympathetic to you. Since you have constant interactions with the police, you do not want to be a problem for them. He made his money asking game show questions to tourists, and if the tourists don’t feel safe, then he doesn’t make his money. One other tip is if you want money, find a couple. If you go to a lone female, you will scare them. If you go to a lone male, they will ignore you. If you go to a couple, then the woman will feel safe but sorry for you, and pressure the boyfriend to give you money. Also, if you are a problem, the businesses don’t want to deal with you. If you aren’t a problem, then you show up at a diner late at night, buy yourself a coffee, drink it slowly and you’ve got a warm place to stay for a few hours. He showed me the routine that he used to get money from passing tourists. That gave him enough money to buy food and booze. Food is cheap and hunger simply is not a problem for homeless people in NYC. The big problems are diabetes and substance abuse, and I suppose being in a mental hospital was good for him not so much because he could get food, but because he got treatment for diabetes.