Bad Programming Practices

Each post must contain one bad programming practice to add to the list. I'll start:

In C++, overload library functions by using #define. That way it looks like you are using a familiar library function where in actuality you are using something totally different.

Writing an HTTP client library and making it impossible to do a simple GET request and put the result into a string in less than 15 lines of code.
I'm looking at you, Java.