Last week, we discussed the conjunctions denn, weil, and da, the most common ways of saying "because" in German. There is, however, yet a third far less common German word that can be translated as "because" in slang usage: darum. But first, let's take a look at the way darum is more commonly used.
The adverb darum, depending upon its context in a sentence, most commonly has a topical meaning as "about," almost always in conjunction with the verb gehen:
Es ging eigentlich darum, Wohnraum zu schaffen in der Stadt.
It was actually about creating living spaces in the city.
Caption 20, Umweltbewusstes Wohnen - Architekturpreis Green BuildingPlay Caption
Or as "therefore, which can also be alternately translated as "that's why" or "for this reason":
Darum nenn mich nie mehr dummes Huhn
Therefore never call me "dumb chick" anymore.
Caption 20, Cosma Shiva Hagen - So trägt man PelzPlay Caption
You sometimes see darum as part of the separable verb darumstehen, which can translate as "to stand around" or "to stand around there," as opposed to the more common herumstehen ("to stand around" or "to stand around here"). Darumstehen can also mean to stand around something, as in um etwas herumstehen:
Wir sehen das Fahrrad und die Kinder, die darumstehen.
We see the bicycle and the children standing around it.
A slang usage of the adverb darum, however, is typically seen as a childish answer to a question, or an answer that is really no answer at all!
Warum hast du das gemacht? -Darum!
Why did you do that? -Because!
Go to Yabla German and search for darum to see the word used in a real-world context. For a more advanced article on the various uses of darum, read this DWDS article.