The Brief: Reeeee is an expression of extreme irritation.
Similar to other exclamations, REEEEE – the number of e’s varies – is another way of saying “ahhhhh.” REE’s origins and connotations within internet culture make it particularly loaded with meaning which is not always intended. Saying “ree” can be a reaction to being provoked or triggered.
When threatened, some frog species emit a screaming sound: “REEEE.” The connection between REEEE and frogs sometimes brings Pepe into the picture, attributing the noise to him and adding another layer of memes.
Sometimes, “ree” is used to mock people on the autism spectrum, supposedly mimicking a noise that someone on the spectrum might make. This variation of “reeee” is overtly offensive and disrespectful.
Internet Subculture Usage
According to Urban Dictionary, REEEEEE is “The sound you make when a normie is in sight.” This suggests that “reeeee” is a reaction when an internet subculture is invaded by someone who does not belong.
More mainstream usages of REE often allude to its roots in fringe subcultures. Some people may use it as exclamation without knowledge of its origins or connotations. On Reddit, reposts are often referred to as REEE-posts. It’s not always clear when a “REE” is just a noise or a reference to one of the specific origins listed above. Reeee can be used seriously or ironically, as a reaction to something online or IRL.