Father Steve's thread on the "Saracens at the door" made me think of how often we fall back on expressions we learn over the years. In a few words the expressions are meant to relay a set of information that a paragraphe would be needed to convey.
"I would eat chocolate off a pig's back" ...you feel like eating chocolate (or whatever else) SO much that even if it was on a pig's back you'd eat it.

BUT, if I think of many expressions I was brought up with, I realize that what is perfectly clear to me and mine, may not be clear or pertinent to others.
"I wouldn't trade it for a piece of land." ...even if you offered me a WHOLE farmstead I wouldn't give up the thing the person wants from me. Now, unless you were brought up in farming country, where land is quite valuable, this would really have no impact on you at all.

What expressions do you commonly use?