We started with Stack Overflow, a Q&A site for programmers about programming questions. StackExchange is an attempt to bring that same technology to other fields besides programming. Cooking, photography, etc. Each of these sites is a StackExchange. Collectively they are the StackExchange Network. So when we say "StackExchange" we mean all these sites, of which there is one big honking granddaddy called Stack Overflow.
The entries in Webster suggest that honking refers to an object making a loud noise, but that meaning seems off in this context.
What does "honking" mean in this context?