a hard/tough _______ to crack
a hard/tough nut to crack
not somebody’s cup of ______
not somebody's cup of tea
spill the _______
spill the beans
a smart _______
a smart cookie
take something with a pinch of _______
take something with a pinch of salt
a piece of _______
a piece of cake
_______ someone up
butter someone up
as cheap as _______
as cheap as chips
as cool as a _______
as cool as a cucumber
the _______ of the crop
the cream of the crop
_______ someone on
egg someone on
bring home the ________
bring home the bacon