Sarah! OMG, when I was younger my parents had a mini schnauzer named Heidi, and she was totally freaked out about anyone blowing on her bum too! She never bit anyone, but she would jump a mile into the air and not come near you again for an hour or more, lol.
Out of curiosity, I tried butt-blowing on our new pup... he was completely unphased. Weird
Lauren & Nikko