A term used by rural folks in years past to emphasize a matter of importance or urgency. An example: 'By cracky, you need to get out there in the field with that mule and plow and finish the sod-busting before dark.'
Meaning an instance of something has just occurred that was previously discussed. For instance, a person may have told another that something always happens. Later that day, they see it happening, and the informer might say, 'case in point'.
If somebody tells you to cast your mind back on something, they want you to think about something that happened in the past, but which you might not remember very well, and to try to remember as much as possible.
The idiom "cat fur and kitty britches" reminded me of this saying that my granny used when asked what was for dinner, and was her way too of saying you get what you're given! This was in Gloucestershire, UK and in the first part of the 20th century.
If something is as clean as a whistle, it is extremely clean, spotless. It can also be used to mean 'completely', though this meaning is less common nowadays. If somebody is clean as a whistle, they are not involved in anything illegal.