Um... im not into the -fur scene, but bringing up this kinda thing is pretty much along the same lines as many secret interests. but first, by mate, do you mean it in the British sense for friend, or for a boyfriend/girlfriend, or a lifetime mate (spouse)?
I was being goofy in the shower and made myself a suds mohawk, she laughed at me and asked if I was secretly a baby fur.
From "I'm too nervous to ask" to "Likes babyfurs but wouldn't want to be with one" to "You must be a babyfur for playing with soap! I love you!" in all of a day.
It doesn't get anymore (un)believable than that.