For a few years, English speaking people in certain online communities have been saying “Oida!”. It is purported to mean “Dude!” and to be a Viennese or Bavarian word.
It has an Urban Dictionary entry from 2008. There was song, Oida Chüüü, released in 2011.
Ewa Placz uploaded a video to Youtube on Oida in 2017.
It is mentioned in this serious-seeming article
It has an entry in Bavarian Wikipedia but the only reference provided is the Ewa Placz video!
The weird and patchy nature of the evidence made me think that Oida started as some kind of weird and inscrutable internet prank. I mean how many German (sensu lato) words start with Oi anyway? None?
Going back through the Wikipedia archives, the very first article on the topic gave Åida as the primary spelling. That would be a normal Austro-Bavarian spelling, and would be pronounced a little bit like an Engilsh “Oi”. Å represents a dark a sound in Austro-Bavarian.
Various sources link Åida to the standard German Alter, meaning old, or old person.