Hi Bita,

It doesn't necessarily refer to bad situations. Many people use this as an expression to indicate that they may have doubts about something they have taken-on (become involved in). For example; you could agree to participate in something and then realize that it involved doing more than you had originally thought, like agreeing to participate in a six mile run, and then realizing that its going to be harder than you thought and that you need to do a lot a preparation training. In this instance you would certainly be asking yourself 'what did I get myself into'?