An Insult in Any Language （まめちん）

He Says:
mame chin　（まめちん）=tiny penis
There is a penis song in which Caneron Diaz and the others sing.
Then they go "Your penis is so big~!!Your penis is too big to fit in here~~!!".
This time,"mame chin" is completely opposite meaning.
Mame means a bean. So it's so small,tiny. If they sang it,like
"Your penis is too small to fit in here~!!".
They say japanese penis are smaller than Americans' in average. Jp guys' penis are said about 5 inches or less.
But mame chin is about 1 inch,like baby size.
If your japanese boyfriend's one were mame chin, please do not say so to your love.
He would be so much hurt by the word from you.
But it would be the best word as a parting shot,"Mame chin!!"

She Says:
I've done extensive research (heh heh) on the myth of the small Japanese penis and I've found it to be wholly untrue. In fact, I would have to say that three out of the five biggest penises I have ever seen in my life have been attached to Japanese men.
Nonetheless, you'll find that Japanese men are totally self-conscious about their size, even if it's normal-sized or huge. And you'll always hear the foreign guys in Japan going on and on about how their Japanese girlfriend said that their dick was SO MUCH BIGGER than Japanese guys' dicks and how they've seen Japanese guys naked in the onsen and can verify that their dicks are small. Well, I've got two little secrets for you:
1. Your girlfriend is bending the truth because she knows it's what you want to hear.
2. Some are show-ers, some are grow-ers dude. And unless you've seen those penises hard, you've got no idea what you're talking about.
I think that telling a guy he's got a small dick is probably a universal insult. Now you know how to do it in Japanese.

This next word is...きもい。