ok i thought of a few while reading this:

"colder than a witch's tit on a winter's morn" ~ from my gramma meaning "its fucking freezing out here"

"slicker than greased dog shit" ~ a friend you to say it all the time, he used it to describe anything really slick (like the bottom of the lake at a drop off) or a guy you would want to do buissness with

"if i could i would but i cant" ~ whats it says

thats all i can think of right now....if i think of anymore i'll post em