I can't help but laugh; this is too funny
Internet slang used when something is so funny that laughter is unavoidable. Often seen in online comments and social media.
See also: 草
This video is too funny, I can't stop laughing lol.
あのコメント見た？草不可避だったわ。
Did you see that comment? I couldn't help but laugh.
草 is the core slang term for laughter (like 'lol'), while 草不可避 is a set phrase meaning the laughter is unstoppable.
Internet slang combining 草 “laughter” with 不可避 “unavoidable.” 草 developed from strings of w, an abbreviation of 笑い, whose appearance resembles grass.