Here is a fun word I just heard:
(from Kenkyusha’s 新和英大辞典)
a drastic change in character
～する suddenly change; change character; become somebody different; change one’s spots
This is an interesting word. First, let’s break it down:
豹 hyou leopard (the big cat)
変 hen change (into)
You may think it means to suddenly become as ferocious as a leopard, but it doesn’t.
The word originally came from a verse in the I Ching 易経 ekikyou (Book of Changes – an ancient Chinese text).
From that text comes this phrase: 君子豹変 kunshi hyouhen which means, “A wise person readily admits mistakes and corrects them.” (君子 kunshi a wise man)
So originally, 豹変 meant “as a leopard’s spots are distinctive, so is a wise man’s willingness to admit mistakes and change them”
Apparently, this word originally had a positive connotation. Now, it is mostly used negatively.
The meaning went from a wise man changing his position after realizing he was wrong [POSITIVE] to a normally nice person flipping out [NEGATIVE].
Yumi used this in reference to our dog, Hana. Hana is always very sweet UNTIL Tevye (her brother) gets too close to her food. Then she really 豹変s.
Here is an example of the current negative usage snatched from the web:
futari kiri ni naru to otoko ga totsuzen taido o hyouhen saseru.
As soon as they are alone, the man suddenly changes his attitude (for the worse).
And it looks like an episode of CSI: New York in Japanese is titled: 「豹変」