I just thought of a funny story... kinda disturbing if you think more into it.
My mother once went into a full blown hysteria, meltdown breakdown, because a person who she wanted to impress told her she looked - Great.
She would talk about this for... months... She expected to hear how she is the most beautiful and amazing looking woman for her age... and the word Great... was disturbing to her and her narcissistic ego. The rages that followed were part-traumatizing, part-hilarious.
If you want to make a narcissist go into a meltdown - treat them like they are ordinary and just normal.