“I’m your Huckleberry” means “I’m the man you’re looking for”, and the line reminded me of a scene 6x18 “Frontierland”, the classic episode in which Dean and Sam travel back in time to the Wild West.
The scene starts with Sam and Dean walking into a sheriff’s office in their search for Samuel Colt. It goes like this:
Dean: Sheriff? Could we have a word?
Sheriff: Depends who’s asking.
Dean: Marshall Eastwood.
*pulls back vest to reveal badge*
*Sam side-eyes Dean*
*the sheriff watches Dean*
*the judge watches Dean*
*the random cowboy watches Dean*
*no one looks too impressed with him*
*Dean nods toward Sam*
Dean: This here’s, uh, Walker. He’s a Texas ranger.
Sheriff: So what can I do for you boys?
Sam: Uh, we’re looking for a man.
Judge: *scoffs* I’ll bet.
*reaction shot of Sam and Dean looking taken aback*
Judge: *nods at Dean* Nice shirt there.
Sam: *looks over at Dean*
Dean: What’s wrong with my shirt?
Judge: *pointedly* You’re very clean.
Dean: *flabbergasted, examines himself subconsciously*
Dean: *defensively* It’s dirtier than it looks.
Note how all the focus is on Dean, even though it was Sam who said the actual line about looking for a man. Gotta love how all the queer subtext is mysteriously dumped on Dean, haha. And if the line’s been used before with a double meaning, then who’s to say it doesn’t suggest a double meaning here, in the show’s second western-themed episode, with “Texas ranger” used as a cover again no less.
¯\_(ツ)_/¯ Just saying