I think 'cuteporcupine' meant that because in the drop down it says carpet and has I/he/she/it/you...by the way, does miffed mean confused? I'm assuming that is a British English term...I like learning other ways to say things :)
I don't know the context of the Portuguese in this case, but "she carpets" is an English phrase meaning "she lays a carpet (or rug) over the floor". When I moved into my condominium, I was required to carpet the floors.
The n comes from the nasal sound in em, shown by the letter m. Just think of it as em > n + o to form no. Sort of like how the m in homem changes to n when it becomes plural homens. Homem + s > homens (m > n before s)