难得一笑 What is a small trick on number 十百千萬 and in English ?

难得一笑 
犬/狗看守器，
类,种类相似,惟犬最甚。——《说文》是說惡狗也忠主人，奸臣易背叛?

Also keep "the lesser  the better" principle as some opponents showed their grin as a remind of
"jiao4chou2--collate as if fighting with an enemy ".