C hacks

C allows you to define a void pointer. This pointer will match a pointer to any type. When you invoke a function whose formal parameter is a void *, you can use any pointer as the actual argument.

This allows you to build generic functions which will operate on a variety of data types. However it does bypass the compiler's type checking - and allow you to inadvertently make mistakes that a compiler for a strongly typed language such as Ada would detect for you.

Hacking

This term probably arises from the MIT expression for what we know in English as a "student prank". MIT students refer to these assaults on the conventions of society as "hacks".