Japan Times ("JAPAN COULD 'CLAM DOWN' ON N. KOREA", 2005-01-20) reported that Japan's powerful diplomatic weapon against the DPRK could be a humble shellfish, if Japan chooses to stop eating them, a citizens' group said Wednesday. Japan regularly imports tons of "asari" clams from the reclusive state. Boycotting asari imports could help Japan find
The story was about clams and they wanted to imply 'clamp down on' while making a pun (clam down on). Newspaper headlines often contain puns, word-play and jokes.