I don't know if "bunny" means "girl" so much as it means "child". If "girl" means "feminine and soft" that isn't it. "Child" in the sense of "I am an unwritten plate tuned to the world with innocence and a sense of wonder. You could crush me with one hand but you won't."
Tell me if I got that wrong Mojo.
You are right in the sense that the word I would use to best describe both "bunny" and "puppy dog" would be "vulnerable". One thing I'm still trying to wrap my mind around is the extent to which men associate vulnerability with feminine sexuality. It is obvious on the basic level of physiology or sexual functioning why vulnerability might be associated with the feminine. I think anyone, male or female, who evinces vulnerability seems more "lovable" but I think it resonates more as "f*ckable" to the male psyche.
Also, the monkey is a child too but more curious, active and high-spirited, the toddler running with scissors and a sucker in her mouth along the edge of the pool in hopes of catching the red balloon.
"Tell me, what is it you plan to do with your one wild and precious life?" - Mary Oliver
