A noun and verb for insult could be "hurt."
A verbal insult is a "slur." An insult may also be a slam, slap, or snub.
They're not shouting the number four. They're shouting "Fore!" which I believe is just another way to say "Head's up!". Since I don't golf, I don't know for sure.
A four-letter verb that can mean "obscene" is "bawl," which refers to shouting or crying out loudly, often in a way that can be considered inappropriate or offensive. However, if you're looking for a verb that more directly conveys obscenity, "cuss" (to use profanity) might be the better choice. Both terms carry connotations of vulgarity in different contexts.
A four letter word starting with the letter a is able.
Four letter words:theytidytinytobytonytorytraytroy
The four letter word is dawn.
The letter "f."
Several four letter words begin with the letter q. However, there are no four letter words that begin with the letter q and end with the letter o.
Haul and laud are four letter words. The 2nd letter is a. The 3rd letter is u.
Some four letter words with the first letter f are:facefadefailfairfallfamefarmfastfearfeedfeelfeetfestfilefillfilmfinefirefirmfishfistflapflatflewflitflipflitflopfluefoalfoamfoldfolkfoodfoolfootforkformfortfourfrayfreefretfromfuelfullfumefuryfussfuzz
Four letter adjectives that begin with the letter f:fairfakefastfinefiveflatfoulfourfreefull
Some four letter words that start with E are:eachearneaseeasteasyechoecruedgeeditelseemitenvyepicetcheuroeveneverevilexamexit
Four letter words with X as the third letter:boxyfoxyluxenextpoxysexytaxitextwaxy