见缝就钻 jiànfèng-jiùzuān
[avail oneself of loopholes] 比喻到处钻营或利用各种空子
看到有利的事物就争取营求。比喻善于投机,不放过任何机会。 如:「他向来喜欢投机,是个见缝就钻的人。」
英语 lit. to squeeze into every crack (idiom), fig. to make the most of every opportunity