Situational Dialogue Exercise
The intent of this exercise is for the character to react to each situation in a manner unique to who they are, or at least to who you have created them to be. Some of these situations are similar, I will admit, but they should prove different enough to help understand the thoughts and actions of characters in their dialogue from their perspective.
Some things to avoid:
Yelling "You B#####d!" any time a disadvantageous situation appears.
The plain-face "Well s##t" remark gets old very, very quickly, and says almost nothing about the character.
Use of "Tch" or "Heh" to represent a tough guy should be sparing, at best. Watch Eastwood. The man hardly says anything at all.
Monologues are almost always unnatural. When was the last time you received a full lecture about how life works and how views are emotionally charged from someone who can't