One idea that comes to my mind is the verb jinx.
We often say that someone jinxes something when something bad happens after that person has made a related comment. For example, in this blog, a blogger writes about tornadoes. On the same day the post was published, one commenter said:
I think you jinxed us. Currently have several tornadoes moving through our area.
Sometimes, though, this phrase is used when a comment is made about how things are going well, and then the situation changes after the comment is made. For example, in a newspaper article about a baseball game:
Manager Kirk Gibson, meanwhile, thought perhaps a reporter was to blame. “I think you jinxed us,” Gibson said. “You were the one talking about how good the defense was playing, right? You should keep your mouth shut.”
The phrase was also explained on an English message board:
When someone says, "You jinxed me," it means you said something, and made it so it might happen. For example:
You: I can't believe we got locked out of the house.
Friend: At least it's not raining!
[it begins to rain]
You: Ugh, you jinxed it!
So, your example about the upcoming raises might happen like this:
Cody: We don't have many customers these days. I hope our boss will not cancel the year-end bonus.
Donovan: Shhh! Don't jinx us!
Note: This is fairly common parlance in the US; I'm not sure about other parts of the world.