Here are a few good ones...i worked with an old man that would drop these little one liners every day. I started writting them down in a book. I have over 200 of them. Unfortunatley most of them are not fit for this forum.
1. He was tight as bark on a tree;
2. He was as nervous as a dog sh-tting a peach seed.
3. Dark as the inside of a bear
4. He's about as usefull as pocket on the back of a shirt.
5. His eyes rolled back in his head like a dieing calf in a hail storm
6. That's as useful as tits on a boar hog
7. I'm so unlucky i could fall in a barrel of T_ts and come out sucking my thumb
8. I'm so mad i could lay down and piss straight up
9. He looked as out of place as a turd in a punch bowl
10. if it hurts...your probably not doing it right