At a local con where he was the GoH, during a Rockband game, I was asked to take on the guitar.
Guy on vocals said "And now we have a bear on guitar!" to which I promptly replied "Bear??! I'm a dog. BARK, MOTHERFUCKER! BARK! Canine; do you speak it?!", a take on the cult-classic line from Samuel L Jackson in Pulp Fiction.
Needless to say, MUCH hilarity ensued for all parties involved.
And this was the final result, which was amazing.