From an interview with a high-school pitching prospect at a Milwaukee Brewers' fan site, "BCB Interview: 26th-round LHP Lex Rutledge", 6/12/2009":
BCB: So, speaking of football and late-round baseball picks, did you hear about this Florida State defensive tackle recruit the Brewers drafted? Jacobbi McDaniel. He's a 285-pound third baseman.
LR: [laughs] No, I didn’t. Dang. Does he even play baseball anymore?
BCB: He said he wants 1.5 million to sign, and now the Noles fans are freaking out because there's a report the Brewers offered him 800k.
LR: Wow. I wish they would offer me that. He must can hit.
BCB: Yeah, no kidding. Gain some weight and become a five-star DT recruit and you can make the big bucks.
LR: [laughs] I just don’t see that happening. Oh well, maybe I can throw 103 and get the big bucks like Strasburg.
There are two links in this passage. The first one is to a note on an FSU fan site, about whether Jacobbi McDaniel plans to play baseball or football. The second one is to a Language Log post by Geoff Pullum, "Do double modals really exist?", 11/20/2007.
In that post, Geoff observed that of 64 logically possible two-modal combinations of the eight most basic modals, very few are actually attested, and most of these are consistent with the hypothesis that might and may are sometimes re-analyzed as adverbs. The quote "He must can hit" adds another combination to the list of attested double modals that Geoff (and others) came up with, and thus bears on an interesting question of syntactic analysis.
The pseudonymous author of the Lex Rutledge interview, "battlekow", is clearly a Language Log reader, who demonstrates that despite the widespread signs of ignorance and confusion about linguistic description, you can find examples of well-informed linguistic commentary in some unlikely-seeming places. In this case, the commentary is nothing but a hyperlink — but that's all that was needed.
[I noticed the link in battlekow's interview, by the way, because our referrer log shows that some 60-odd readers have clicked on it. And I should add that I've always thought that double modals exist, so I was glad to see this one, and feel that the others ought can be found somewhere…]