[Contextualisation, for the others]
OP is talking about what’s called “trote” or “praxe” in Portuguese. It goes from a genuine welcome party to hazing; it depends a lot on the uni and the grad. From personal observations, hazing is way more common in Medicine and the engineering grads; and hazing is banned in plenty unis, under threat of expulsion.

My experiences in both grads (Chemistry and Letras*) were rather good. In both the common element was the toll, where freshmen and veterans organise themselves to beg money on the streets for booze, with painted faces. Then everyone drinks together, and the ones who don’t drink alcohol can drink soda instead, nothing is forced.

In Chemistry the veterans were prone to a few practical pranks, but nothing abusive, like:

• to dress as a teacher, and apply a fake exam/test on the freshmen, with content from the third year, just to see their desperation;
• to sell boxes containing “80% pure nitreto de azoto”**, claiming that they were necessary for the graduation. (They were dirty cheap, and nobody believed the bullshit - the ones buying it did so to fund the academic centre).

Then as a Chemistry veteran I helped with the toll. It was mostly making sure that the freshmen were safe, happy, and hydrated, or redirecting them to better crossroads (higher traffic, lower speed). Then getting drunk and babbling about the Celtic culture with one of the freshmen.

As a Letras freshman, I actually helped more from the veterans’ side of the things than begging myself money, given that I already had some experience with this. Then spent quite a bit of time taking care of another freshman, who had too much booze and was crying “nooo I drunk too much, and my mum is coming to take me back home, what if she sees me drunk?” (she simply laughed it off).

*Letras (“letters”) is a typical Latin American grad including linguistics, translation, and literary criticism.

**“azoto” is a valid name for nitrogen in Portuguese, but it’s almost never used where I live. The veteran exploited that to make atmospheric dinitrogen sound fancy. 80% dinitrogen = air.