The lock is 'tricky' to open.
a 'tricky' subject/question
a 'tricky' intersection
(..) - Yeah, it is. What? Well, here we sit, devil-may-care... ...and a while ago you were reattaching Simone's spinal cord. That was a tricky one. In reality... ...that operation takes hours. But they only showed it for minutes. Who's "they"? No one. (..)1996 TvShow: Friends Title: The One After the Superbowl: Part 1 Season: 2 Episode 12