Mamo = a changed version of the word mama which means mum in romanian. Its usually used in the saying; Mamo mai por ca tine. It ussually means a slang for "pog" or "happy" .
Matacios = being rude, bad, a jer, a dick etc
Comes from the saying of "Ma-ta", or "mamo".
The word started as a meme created by fellow classmates in a group.