It occurs to me that over the years, I've probably experienced just about every possible means of screwing up a fishing trip. From literally dropping a boat off a trailer while doing 70 mph down the highway, to getting my the index finger on my stripping hand smashed in a door on the first day of a weeklong trip to Florida. I've gone on trips with guys who really only wanted to drink rum and play poker (or chase strippers, not stripers...) and I've seen guides that ought to have been institutionalized.
Now I've got nothing against rum, in fact, some might say it's made me the man I am today. But let's face facts, some people have different priorities. For me, fishing comes first. I'll also admit to having had no end of fun with hungover buddies, especially when I used to tuna fish (hey buddy, time to cut up some more chunk bait). That said, I'd rather not hear about the hangover. Whining should stop at the dock, and better yet, at the door of the house, before you get in the car with me.
So what other ways can you screw up a trip? Here's a list of just a few... Leave the crank handle for the trailer winch in the garage. It's always fun cranking the boat on the trailer with vice grips. Stick your fully assembled fly rod in your backpack as you hike down to Gay Head, so it sticks up 7'over your head. Forget to duck under trees. If two pieces is good, then three must be better. Leave everything on the roof of the car and drive off...rod, reel and fly vest (okay, I haven't done this one, but watch the forums, we get 4 or more posts a year about guys looking for their gear). Try taking along a wife/girlfriend/etc. who really has no interest in fishing. It's a nice varient to the kids constant refrain of "are we there yet?" - "Can we go yet?" Even worse...take along a buddies wife who has no interest in fishing. As I said before, whining should stop at the dock. Forget to wear sunscreen on the first day of a weeklong trip. That purple-ish, rare steak color looks really good in the photos later. Plus the memory of the pain and sleepless nights, and days spent huddling in a corner of some motel room will last for years.
As the old line in Cannonball Run goes, "What's behind me does not matter." But in fly fishing, you've generally got a guide, a buddy or worse, your wife, standing in the boat behind you. You have not lived until you've had to remove a hook from your wife or girlfriend. Trust me.
Running out of gas, in the tow vehicle, or worse in the boat. Boat fuel guages are notorious for not working well, if at all. Also, many of us forget that the last 1/4 tank of fuel probably won't come smoothly out of the tank in any kind of sea at all. In the truck, you may forget that you're not going to get the same gas mileage you'd normally get. Hence, that one tank trip often takes 1.5 tanks. If you don't watch the guage, you're in for an interesting time at the side of the road.
Spend a boatload of money traveling a long way away and don't bother hiring a guide for a couple hundred bucks. After all, who'd want to ruin a fishing trip by actually catching fish? Sleep late and quit early. Even worse, don't go out at all. Let's face it, if you aren't out fishing, you might as well be working.