sell nba tickets or nfl on ebay , or some popular world cup any sport, and then you dont send any tickets bc you never even had them.
can also set up a travel agency and offer underpriced holdidays, at first you make some minues until you got plenty clientele, and then when you got plnety, after making as many as possible pay unfront, you declare bankrucpcy.boom.
you didnt specify if you mean making it legaly,so yeah