Club Mate is a "cult drink" in Europe (especially Germany) among fans of rave culture, electropop and digital gaming. The soft drink contains half the amount of sugar compared to other popular energy drinks, like Red Bull or Monster, but double the caffeine of a regular Coke or coffee. So, you'll get a kick without the sugar high.
Enhanced by Yerba Mate, the South American caffeine herbal tea. Combines well with gin, vodka or tequila, if you like mixed drinks. Club Mate was prominently featured in the movie "The Social Network" (about the beginnings of Facebook).