The Brief: Online, the word "woosh" refers to when something has gone over someone's head.
“Woosh,” sometimes written as “whoosh,” is an onomatopoeia of the sound something might make while flying over someone’s head. Online, it’s typically used to reference when a comment or joke has gone over someone’s head.
The subreddit r/woosh, which is dedicated to posts where people completely miss the joke or the point, has over 197,000 members. Outside of this subreddit, people often use “woosh” and “r/woosh” synonymously.