Somehow Vegeta crossed over into the universe of jujutsu Kaisen and ran into Yuji. Yuji Itadori not knowing who Vegeta was asked if he was a new teacher.

Yuji: hello sir are you a new teacher at the school

Vegeta: No I am the Prince of the Saiyan's, I don't know how I got here, I was training in my chamber and then I ended up here.

All of a sudden a voice started speaking from nowhere, of course the king of curses

Sukuna: oh so we have some new monkeys in the school, you're a Saiyan right?