tough egg to crack

tough egg (to crack)

A person, thing, situation, or problem that is particularly difficult to understand, solve, or deal with. I've been dating Jenny for over a year, and I still think she's a tough egg to crack! Figuring out the best way to modernize our product without alienating existing customers is definitely a tough egg to crack. The spy we captured is a tough egg; he hasn't said a thing since we began the interrogation.
See also: egg, tough

tough egg to crack

and tough nut to crack
n. a person or thing that is hard to figure out or hard to deal with. She won’t talk. She’s going to be a tough nut to crack! I wish Jill wasn’t such a tough nut to crack.
See also: crack, egg, tough
References in periodicals archive ?
"Hersey's singles lineup is a tough egg to crack, so our doubles (teams) needed to really step up and deliver wins, and that's just what they did."
The fact my grandmother probably understands more about blu-ray players than me means I may be a tough egg to crack.
However the 26-year-old light-heavy prospect admitted that 36-year-old Okoth was a tough egg to crack.
What those costs will be, however, remains a tough egg to crack for the moment; the price-tag will be determined once production begins, the Riva Palacio brothers say.