One from my late MIL. She'd come inside during the winter and announce "It's slick as a greaser out there." The only use of 'greaser' I had ever heard of was an insulting epithet and couldn't understand why a nice woman like her would use such a word. I eventually found out that the 'greaser' to which she was referring was a chunk of ham or bacon rind kept to rub on a griddle or frying pan.