I wonder how weird that'd feel, sitting half in and half out of the portal, with a pony front and human butt, or possibly the other way around... Oh god, what would happen if the portal shut off if you were halfway between, like if someone took out the book on Equestria's end, or sucked out the magic on CHS' end like what happened in Friendship Games? Would you get cut in half, nothing happens, or end up some human/pony hybrid, like a satyr or centaur?