HAHAHAHA. Oh man. Considering how Frankie reacts to all kinds of perfectly innocuous things, he doesn't seem all that upset. And Hugh. What does Hugh do? He does Paul Gross Arms \o/ :D And Hugh totally knew what slash was, which leads me to believe a) either Frankie told Hugh as soon as he found it (I enjoy that imaginary conversation), or, considering he mentions Harry Potter a lot, b) Hugh is well acquainted with it.
I really love that, normally, comedians just don't give a fuck. In fact, they're happy to actively encourage slash.
Yeah, there's no way I'd ever bring up slash with someone who might possibly have it written about a character they play/them (awkward much?), but if they find it by themselves and don't mind, I always find it hilarious.