Think of any time you stubbed your toe, chances are you screamed angry gibberish when you did.
This trope is the inspiration for "wharrgarbl," used as a shorthand in some circles to denote nonsensical political ranting, and often associated with an image of a dog drinking from a high pressure hose.◊
When a person is especially angry online, they may try to convey their anger through text by mashing their keyboards to create a string of complete gibberish. For instance: S:DLGIhdsf;glkihdrsglko;"RbgDSR":HDShgs Appropriately enough, it's called "key-smashing."
Chilean Spanish is often mocked online for the way their speakers degenerate into Angrish. "LA WEA FOME WEON CULIAO SACOWEA VALIS CALLAMPA AWEONAO CHUPAI PICO PO KISAWEA WEON LKSADKLASDKJSAKJSAKJSAKJSASAKJSAJDAFNHKJDSAKK"note The cleanest translation would be more or less "This is boring, you suck (literally and metaphorically), what the hell is this, man" with significantly more profanity. Doesn't help that spoken Chilean also sounds like this, even if the speaker ain't actually angry.
In his first autobiography Moab is my Washpot, Stephen Fry recounts a time when he was so angry at seeing some youths throw stones at ducks in a park that he threw some stones back at them while yelling "'You shit-spike-wank-turdy-bastardheads! How do you fucking like it, you tossing tossers!", and similar "meaningless obscenities".
Dennis Green's bewildering "They are who we thought they were!" post game rant.
Go on the internet and tell me that you didn't encounter someone making an angry comment that's too ridiculous to read or write. Even downplayed examples can be found in folks with usually impeccable punctuation and proper use of caps suddenly losing both.
The Bicol Language from the Philippines has something called as an Angry Speech Register recognized by researchers. It is locally known as tamanggot (lit. "angry words") and it's possible to construct entire sentences using angry variants of normal words. Though most often used in anger, it can also be used for humor or to grab attention. Here are someinformation on the subject.