Literally someone with large testicles: a vulgar term for a dumbass, moron, or idiot. (In Colombia, it is also extremely common as a casual way to address close friends, similar to dude).
A clueless or stupid person. It is also used as a friendly, informal greeting. (In Costa Rica, it is a very common way to address friends, similar to dude or man, despite its vulgar origins).
An affectionate and informal way to address a friend in Venezuela, equivalent to dude or man (used frequently between close friends despite being a vulgar term).
An insult used to call someone useless, stupid, or incompetent. It is a very common way to berate someone for their lack of ability or for being a dummy.
A casual way to address close friends, similar to dude or man, used as a synonym for the Colombian term parcero. (Although the word is literally a vulgarity referring to testicles, it is a standard informal greeting among friends in Colombia).
A term used as either a friendly greeting or an insult, depending on context and tone. It ranges in meaning from dude or man to dumbass or idiot (In Colombia, the word is ubiquitous and its severity depends entirely on the relationship between speakers).
Guevón! Let's go to a party tomorrow! He is such a guevón, playing the victim just to avoid fixing the problem.