Expressions that don't directly translate

So I was talking with a Japanese friend of mine.

I was explaining that when you are on-stage, if you are nervous, traditionally (at least
in America) you just imagine that everyone in the audience is wearing underwear.

In Japan, the equivalent expression is "Imagine that everyone is
a kabocha (Japanese pumpkin)".....lol.....

Anyone else find any funny expressions in Japanese that are totally
different from the one in your native language?

Thanks.