19th century slang which was popularized more recently by the movie Tombstone. Means "I'm the man you're looking for". Nowdays it's usually used as a response to a threat or challenge, as in the movie.

I'm your huckleberry comes from a very classic and hot western movie called tombstone. this phrase means I'm the perfect man for the job.

You play 'Tom Sawyer' and I will be your 'daddy' in this game as Tom 'kinda' looked up to Huck (in my humble opinion). Ala Mark Twain.

And I will jump into your game Like 'Huck Finn', and give you a "shel·lack·ing" (As the most Hon. Sir Sean Connery could only say properly). And we will "tear-this moTHa-out". +))