If I may jump in for a second and give my answer also.
Yes, I'm familiar with it. Unreasonable is surely a measure of degrees however you are applying the scientific method outwith its area (namely that of prediction based on previous observations since that is what it is designed to do). Do I think there is an orbiting teapot - probably not but I don't know and the answer is unimportant to me until and unless it is about to crash into the Earth or into me - therefore I am agnostic about about Russell's teapot since I would never concern myself with the question except in such discussions.
//edit and this is why I'm basically agnostic about every religion I've ever heard of, some of them have what seem like nice ideas but they barely impact on my life in any way so why bother concerning myself with them aside from the fact I love a good debate.