Online, I've been called Matt, Kamie (the two most common ones), Matthew, Squirtle dude/guy/man, Matej (my actual name), and that's about it, I think. Oh, and there's the occasional Matty.
IRL, I've been called Matej, Tejko, Matejči/ček, little guy, *insert last name here*, Mr. Hawaii Shirt and Matty (even though only one person IRL calls me that)
The names that are underlined are the ones that will get you hurt upon use. Do not use them.