"Shit get's deeper" is an expression used to mean that a situation is more complicated than you originally thought. Usually for something bad. This is an expression you may hear in movies or that you can use with friends but not in a professional situation. Another example of this expression: "I found out, not only did my husband cheat on me, he also got the other woman pregnant." "-Damn, shit sure gets deeper. I'm sorry to hear that." "Supposed to" means "should" or "ought to". Such as: "We are supposed to wash our clothes at least once a week." "One is supposed to work to make money." This expression can also be used in the context of someone expecting you to do something. Such as if your mom wants you to come home at seven o'clock but maybe you don't want to. You can say "I'm supposed to go home at seven." In this context it is slightly different than "should" or "ought to". As a related note, "should" and "ought to" are used for times when you both are expected to do something because it is the right thing to do, and you agree that it is for the best.