Popular Kick/Twitch streamer "YourRAGE" popularized this term. Stemming from his expression "OH MY", his stream chat copied his expression and typed it as "O MA". This spelling of the popular expression paved the way for much more nuanced usage of this word. O MA has been used multiple times by streamers and non-streamers alike. Kai Cenat, Agent00, and many others took this expression and therefore their chats adopted this expression. YourRAGE detests this word from becoming mainstream, so not many people know about this word outside of the W/L community on Twitch.
"O MA" can be used in many ways, but mostly used for twists or very surprising events where you would use the word "Oh My!". Due to this very comedic way of saying this common phrase, it is acceptable to even say this in slightly surprising or awe-inspiring events. This would classify it as a "Filler Word" and therefore, slang that can be shaped and molded to whatever the speaker has in mind.
"O MA" can be used in many ways, but mostly used for twists or very surprising events where you would use the word "Oh My!". Due to this very comedic way of saying this common phrase, it is acceptable to even say this in slightly surprising or awe-inspiring events. This would classify it as a "Filler Word" and therefore, slang that can be shaped and molded to whatever the speaker has in mind.
Example 1;
Video: "Competitive art used to be an Olympic sport."
YourRAGE: "O MAAA"
Example 2;
Person 1: Did you see the new 2k game that just came out?
Person 2: Nah, 2k fell off since 2k16.
Person 1: O MA.
Example 3;
Movie: *twist occurs*
Reactor: "O MAAAAAA"
Video: "Competitive art used to be an Olympic sport."
YourRAGE: "O MAAA"
Example 2;
Person 1: Did you see the new 2k game that just came out?
Person 2: Nah, 2k fell off since 2k16.
Person 1: O MA.
Example 3;
Movie: *twist occurs*
Reactor: "O MAAAAAA"
by schoolership March 22, 2024
Get the O MAmug. 
When a man with the biggest head in the west attempts to insert it into a womans vagina and having it violently rip open while his parents watch.
by It's ya boiii November 22, 2021
Get the Dirty O-dogmug. a kid who plays games in class along with Nathan, one time, his friend tried playing a game, but he got caught, like bro wtf.
by A guy in school March 21, 2023
Get the Daniyal Omug. no me compraron una farma con frogas, un volcano y una muna, estoy "depresionada(o)" equisde xdroriando
by crazycray20 April 6, 2021
Get the depresionada(o)mug. Not to be confused wih the suggestive word "Big O", this is a show where Roger Smith does random shit accompanied by a beautiful android. However every character is probably aware of the fourth wall and try too hard not to break it.
John: Did you see The Big O?
Fanny: It's only a decade-old anime.
John: But it's one of the mindfucking show I've ever seen.
Fanny: It's only a decade-old anime.
John: But it's one of the mindfucking show I've ever seen.
by Leviaiz December 30, 2021
Get the The Big Omug. Usually a video game censoring "hell" from "hello" because its censoring system is very oversensitive.
by squidb_ll October 5, 2020
Get the ****omug.