Spanish varies from country to country somewhat more than English does. For example, the plural familiar form ("vosotros") is very common in Spain and virtually non-existent anywhere else. Another verb form, "vos," is more obscure; it's used a lot in Argentina, and less so in Chile and parts of Central America (especially among the rural, poorer classes). Other places it's unknown. Many Spanish instructional textbooks don't even mention the "vos" form, and those that do, do so only in passing.
("Vos" is chiefly known to the Spanish-speaking world from Argentinian soap operas and the immensely popular Argentinian comic strip "Mafalda.")
"Vos" is an alternate form of the well-known singular familar "tu." Structurally, it's pretty similar to "tu"; the chief difference being in accent and in the fact that verbs don't change their stems, as they do with "tu" and other persons.
For example, to say "you think" (the verb "pensar"):
tu: Tu piensas [too pee-EN-sahs] vos: Vos pensas [vos pen-SAHS]
Or, similarly, the command "sit down" (the verb "sentar"):
tu: Sientate [see-EN-tah-tay] vos: Sentate [sen-TAH-tay]
Now, the verb "colgar" means "to hang." Granted, you're unlikely to do so, but if you wanted to say "hang yourself" you'd do it like this:
tu: Cuelgate [kWEL-gah-tay]
But in "vos," it's:
vos: Colgate [col-GAH-tay]
Three guesses as to what the best-selling toothpaste in Latin America is. Hint: it's not Crest.
P.S. To avoid flames (though it cheapens the story somewhat), I should point out that "colgar" means to hang an object; the verb "to hang" in the "Occurrence at Owl Creek Bridge" sense is "ahorcar." However, once in a while even native speakers will use the wrong verb--just as native English speakers will use "hung" when they mean "hanged." (The latter is correct for hanging people.)