Phonetic loan from English 'drama' — 抓马 sounds like 'jua-ma', close enough to 'drama' for Chinese netizens to adopt it as slang around 2017. CC-CEDICT tags it (loanword) drama / dramatic / exaggerated.
usage
Overlaps with 戏精 ('drama queen' / drama-machine person) but 抓马 describes the situation/behavior while 戏精 describes the person. You can say 他很抓马 OR 他是个戏精.