"A horn! a horn! my kingdom for a horn"

A couple random reasons for nearly not passing your State Vehicle Inspection :

1. the threads on your gas cap are not "big enough".  This actually happened to me last month and it was a first.  I'm there at the service station - a truly captive audience since my car and all my keys are 8 feet off the ground - and the guy's standing there with my inadequate gas cap in hand asking me if I want a new one or if I want to fail the inspection.  

"Well how much do you charge for a new cap?" I asked, and to myself "...that I suspect you now keep a handy inventory of around the corner!"   I suddenly felt like Clark Griswold after he drove the family truckster off the desert road and found himself in front of the shady mechanic who demanded all his money for the repairs:

Mechanic: Ain't never seen anyone so shit-all stupid as you driving off that road.
                             You musta got manure for your brains.

Clark: Yeah, well, we're from out of town. How much do I owe you?

Mechanic: How much you got?

Clark: No, I'm asking how much the repairs are.

Mechanic: I'm asking how much you got!

Clark: You're out of your mind. Look, I don't have time to fool around so how much is

                    it?

Mechanic: All of it, boy!

Clark: What does the sheriff think of your business practice?

[Mechanic laughs and shows his sheriff's badge]

So I paid the $8.99 for the new and improved gas cap that looked oddly similar to my old one and went on my way with my passing grade.

2. your horn is too weak.  I guess I can understand this one because it's probably a safety issue, but when it happened to Eddy this morning he was a bit at a loss as to what to do next...  So he came to Mechanic Mikie and what ensued should really be the next entry on "There, I Fixed It.com" although since there was no duct tape invovled I think that's an automatic dismissal:

          Eddy: So they said my truck wouldn't pass inspection with the horn not working... Got
                   any ideas?
          Mikie: Have you checked the connections?  Let's do that first...
                    [They check the connections, realizing the horn is shot] 
          Mikie: I think I've got an idea... 
          Eddy: [Giggling as he knows with Mikie that could mean anything] Okay!

The end result?  Eddy's vehicle is now equipped with a boat horn...  Guess that's what happens when you go to a nautical store to outfit a truck...  And in case you're wondering if that sort of thing is acceptable per the Texas Department of Public Safety, just ask newly legal driver Eddy to give you a demo!