Often misused by anglophones, the more literal translation of this
French phrase would be "
isn't it?", applicable
only after an assertion of something that a thing
is.
"Ce chat est bleu, n'est-ce pas?"
"This cat is blue, isn't it?"
The phrase is not appropriate for use after assertions of characteristics belonging to me, you, us or them, only to it, he and she.
"Je suis la banane de ton père!", for instance, would be a poor provocation to this phrase:
"I am your father's banana! ...isn't it?"
Somewhat of a non sequitur results.
"Cela c'est la banane de ton père, n'est-ce pas?" would work much better:
"This one is your father's banana, isn't it?"
(Or, if you insist on being his banana, the appropriate cap for "Je suis la banane de ton père" would be ", ne-suis je?" - the DEVO-esque am I not?)