Meetings, service, and a$$emblies are all too common, and once you have seen one, you seen 'em all. There is nothing worth listening to the second time. But, here are some suggestions of ways to pass the time. The problem is that the attendants might bust you, and make trouble for you. And, of course you should not do anything that might damage the facilities or unnecessarily endanger lives or safety. (Disrupting the program, if you can do so without getting hounded by the attendants, is OK).
For a meeting, it is difficult because the attendants are right there. You can read a book or magazine, preferably one not published recently by the Watchtower Society. You can read the Bible in context surrounding the verses that are cited. You can look up scriptures in the references, butr bear in mind that you should read whole surrounding blocks instead of just the cited scripture to get the most out of it. If you can hide it, a headphones with real music or a recording of an apostate document is a good idea. Game Boys and Rubik's Cubes are risky at meetings since there are too many attendants.
For service, this can really be tricky. The best bet is to have an endless series of errands to run. Get your time started by knocking on a door, preferably one where you know no one is home, and then lead them on one wild goose chase after another. Playing with calculators and iPods is another way to pass the time. Read the Bible, again paying attention to surrounding text. Read out of date Watchtower material or material that is not published by the Watchtower Society. Play the radio, preferably on some dirty music. If you are alone in the car while everyone else is in on calls, setting the radio to come on some dirty music or fogging up the windows is a good idea.
While actually walking, pay attention to the scenery. This is easier in the country. But, even a city has hedges, trees, small lawns and flower beds, and pavement features. Some of the houses are interesting, but just don't fantasize about owning it after Armageddon (you will be building a new one, if they allow it; more likely they will assign you a house that is a piece of crap). Or, in winter if there is ice and snow, you can have a little fun paying attention to that and maybe even sliding on the ice. Of course, there are rules against this, and elderly people need to watch out because a fall can mean more than just a dirty suit.
At a$$emblies, it is a little easier, especially if you sit near the back and they have a FM transmission of the program. Get that iPod out. You can play that GameBoy--I recommend Pokemon because it's such a long game (you can play any game that has a long storyline). Reading any book or magazine, preferably not one that is recently put out by the Watchtower Society, is nice. Now is the chance to get out that old King James Version of the Bible and read that, along with surrounding blocks (just don't try to keep up with the program. If you are in the middle of reading one block and the program goes on, just let it go. That will help you get the context of the message). Most toys and games are OK as long as they do not go flying where you could lose them or make too much noise and attract the attendants' attention.
Or, you can try to disrupt the program. If you are good at making and flying paper airplanes into the stage area, that is a good idea. Bring a ream of plain paper (the cheapest you can get will do). While they are making the opening talk, start folding and flying the airplanes onto the stage. You get extra points for disrupting the sound system, knocking down a microphone, hitting the speaker in the eye, or causing unwanted laughter in the audience that disrupts the program. Just bear in mind that the attendants will soon take care of the disruption, and getting disfellowshipped is not out of the question.
Noise is also possible. I do not recommend lighting a cigarette to which a match is attached and putting it in the contribution box because the building owner will get you for that, plus you could cause injury. What is possible is to set a little radio under one of the seats in the bleachers, set to a moderately high volume. This will not be noticed while people are talking, but once the prayer starts, it will stick out like a sore thumb. Hiding a radio under the platform or near the sound system, or connecting it up so you can remotely activate the sound system to play swearing, will make for disruption. Keep in mind that you might well lose the radio, and they could kick you out and disfellowship you if you get caught.
If you have children, they should have plenty of age-appropriate toys to play with. For small children, a scratch pad with plenty of pens, pencils, and crayons is nice. Having plenty of these is necessary--a rule of thumb is about 4-10 times as much as you think you might need. Bear in mind that pencils break or need sharpening, crayons break, and all the above can get lost so you should have extras on hand. Older children might enjly dolls, video games, and other toys. As with the paper, you should always have 4 times more than you think you might need. I recommend Pokemon, especially Diamond and Pearl since it is such a long game, and people can trade with others nearby with minimal chance of getting busted by the attendants. Other adventure games are OK, but bear in mind that what might take a month while you are at home might go by in one day of a 3-day a$$embly due to the monotony of the program. A good rule of thumb is, allow at least 8 hours of play time per day of a$$embly plus another 4-6 hours per day after to pass the time spent traveling. An adventure that takes at least 40 hours of play time to complete will do nicely.