be on to =
1.be aware of or have information about
2.discover something important or profitable
我有种强烈的第六感知道重大的事儿会在这彩票上发生
In more of case, you should believe your gut feeling since your sense usually is right.
For example, as soon as I finished shopping I had a gut feeling that my new bicycle was gone, and then I saw nothing was there. It happened in the summer of 2010.