At age thirteen, he illegally crossed the Yugoslav border into Italy just to show that he can circumvent SFR Yugoslavia's strict exit rules.

Together with Beli, the four men in their twenties formed an organized criminal crew in the Voždovac neighbourhood that would eventually expand into a mafia clan.

Giška's relationship with other prominent members of the Belgrade underworld was marked by alternating periods of close friendship and vicious feuding, often with deadly consequences.

[citation needed] In the late 1980s, together with gangster Željko "Arkan" Ražnatović and painter Dragan "Tapi" Malešević, Giška ran a nightclub called "Amadeus", located in the Belgrade neighbourhood of Tašmajdan.

[3] Božović, as well as the rest of the Yugoslav underworld, was frequently contracted by the SDB for the elimination of the political dissidents and state enemies.

One of his famous actions involves planting a remotely controlled exploding phone at the door of the certain Albanian emigree in Switzerland as the warning sign.

Božović apparently had a change of heart in 1986, when he was sent to Australia to assassinate Momčilo Đujić, a controversial WWII military leader and an influential figure among the Serbian emigration.

Among the rising stars of Belgrade's underworld, such as Aleksandar Knežević "Knele" and Goran Marjanović "Bombaš", Giška was perceived as a legend.

He is widely remembered for preventing the crowd to enter People's Republic Assembly saying, 'We will not allow for the loss of any Serb life'.

Mutual friend, Serbian rock star Bora Čorba, in an interview in 2013 stated that he tried to consolidate the two, claiming Arkan was willing to do so, while Giška refused.