One phrase that I use all the time is "I nearly **** and fell in it" which, translated to normal folk speak, means that I was very surprised.
Another is one that I picked up from my Grandad when I was very young. It was kind of a threat type of phrase that usually resulted in people just looking at you like you had lost your mind:
"If you ain't careful, I'm going to slap a hairlip on you that will whistle like a 16-penny nail"
I have not the slightest clue what it means but it always made me giggle.
One more is one that I picked up while I was working in prison that is used when someone is telling you about something that they did or said. I still often use the phrase "I ain't mad at you" which actually means that 'I get it and I agree, I would have done/said that too'. Though that explanation isn't terribly clear. Here, I'll try to put it in a conversation.
Person 1: So the guy said my horse was crap and I told him to buzz off.
Person 2: I ain't mad at you.
Ooh, one more from prison life: "You got life f**ked up". I use this when someone who I have no respect for tries to give me orders. Here's an example from when I tried to go back to waiting tables (I quit within minutes after this happened).
Customer: I want my ranch dressing NOW! (after he had already grabbed me by the arm)
Me: Boy, you got life f**ked up. You want it that bad, there's the kitchen. Your legs ain't broke, go get it your own **** self.
Anyway, share some of yours.