Help seriouse question i went to a night club underaged and was offered a white powdery sustance?

ok so i went to visite this nightclub while i was visting my hometown medellin and sat down next to these two friendly guys and we had a few beers and talked (he payed) and next thing i know they slip me something that looks like powder or something in a small zip lock bag what could it be and what did they want me to do with it,i didnt try it because a friend of my big brother passed it back but im curiouse to know what was it?BQ igot kicked out because the guys were going to start a fight with him