Hello again Adam.
I'm noticing your questions are about deep slang french words, aha :).
OK...Though the previous answers don't seem to really want to say it, i'll do.
You can litterally translate it by "merde" (as a noun). But it is very rude, pejorative...I think as much as in English "shit".
You can use it with close friends (bros and bitches, to make a reference to your previous questions) and family you get well with (brothers, sisters, cousins, parents - if you consider them as bros - ...), with anyone else...you'd be considered as a very rude person, except if they are close to you and you get well with (I might repeat myself here, but it's important).
In this context, any of the examples given by Arnaud, "truc" can be replaced by "merde" (noun). It would work !
Other example, a girl is telling her ex to get out of her house and take his stuff with him like "Take your shit out of here and get the f* out!" -> "Prends tes merdes et casse-toi !".
Another one...you come home and you see your sister/brother has made a cake. You see it on the table and say "What's that shit?" -> "C'est quoi cette merde ?" I think we both agree : here, it is a bad move and can hurt your brother/sister feelings (in English and in French).
Be careful though...We, french, are not used to hear a so deep slang from a non-native french. It might surprise us a bit !
Have fun with it, but with caution !