Snapchat is infamous for basically being a sexting application. For those who don't know about it, the app let's you send pictures that disappear within three seconds. This has made people comfortable with sending pictures of their naughty bits because they know they won't live forever.
Seems like that's not the only use for the app though. Financial analyst Jim Cramer recently stated that Wall Street bankers are using Snapchat to make insider trading easier.
Insider trading is when someone buys or sells a stock or financial instrument with non-public information that gives them an advantage. For example, if you knew that Apple was going to announce they were going broke tomorrow and you sold all your stock today, that's insider trading.
Regulations make that kind of trading illegal because it gives people an unfair advantage and disrupts the financial markets. If it were legal, the market would be a disaster.
However, it can be very profitable if you get away with it. That's why, according to Jim Cramer, bankers send each other Snapchats of what stocks to buy / sell and when. The image disappears after a few seconds and no one knows about it!