This looks like a C macro. Basically what it does is replaces the word “true” in the code with (rand() > 10). The rand() function will return a random number from 0 to 32767. So (rand() > 10) will very likely return “true” but not always.
So say you have some code like this: if (someVar == true) { // Do stuff } It would replace “true” with code that usually evaluates to “true” but not always. So every so often your code would just do the wrong thing but it would be hard to debug because it would be rare.
Granted, in that example you probably would just write “if (someVar)” making this moot, but there are more realistic cases where you’d use the constant “true”