I just found this word in the Dictionary, I have no doubt I won't forget it quickly just because of the amusing context.
Literally: surprising box; frightening box
Can you guess what does it mean?
Here you go:
In case you don't know, a jack-in-the-box is a children's toy that outwardly consists of a box with a crank. When the crank is turned, it plays a melody. At the end of the tune there is a "surprise", the lid pops open and a figure, usually a clown or jester, pops out of the box.
Yet again, Japanese names for things are pretty much exactly what they are :)