1. Proud Papa. This is the man (or woman) who holds junior on his lap -- well, during takeoff and landing, anyway. Otherwise, he is content to let his brat "wander," which means the tot uses your knees as a delightful new gym toy, or constantly tries to get your attention with little jabs or gentle kicks. Junior is invariably in diapers. Sometimes they aren't changed quickly enough. Unfortunately sometimes they are changed -- right next to you. Bonus Points: Proud Papa deposits used diaper in your seat pocket.
2. Life of the Party. It doesn't matter if your flight takes off at 6 a.m., this middle seater is on vacation, and it starts right now. He's slamming down Jack Daniels faster that you can down your $2 Coke. He slurs, he spills, he's outta control. And he's just getting started. Bonus Points: Life of the Party starts getting a little green, he's starting not to feel so well, he's … oops!
3. Jack in the Box. This middle seater has a lot of important things to do during the plane ride, including making out a grocery list, playing Solitaire on his laptop, updating his Christmas card list and everything he needs to work with is -- you guessed it -- in the overhead bin. So, he gets up -- to grab that pencil. Wait, he forgot his pad of paper -- up again. Wait, he needs the laptop -- up again. Wait -- well, you get the picture. Bonus Points: Every time Jack opens the bin, something falls on your head.
4. Fool for Fifi. If you're lucky, you'll never know your seatmate is traveling with a dog in a carrier. But of course, you won't be lucky. Fifi will bark, howl and make interesting gastrointestinal noises for the entire length of the flight. Then Fool will take Fifi out of her carrier, so you two can "make friends." Bonus Points: You will be assaulted by unassailable olfactory evidence that Fifi hasn't been let out for a walk in a long, long time.
5. The Bean Burrito. Your frugal seatmate brings his meal on board, and it is invariably a very large bean burrito. Within minutes of consumption, fumes begin escaping -- and your seat becomes a kind of death trap. Bonus Points: Burrito's beans are heavily laced with garlic and onions.
6. Barefoot Boy. This is the passenger that dislikes wearing socks with his shoes. He also dislikes wearing shoes and will slip them off just as soon as he's seated. You will then discover that he doesn't like bathing all that much, either. Bonus Points: In lieu of regular hygiene, Barefoot douses himself head to toe in that after-shave you used to give your Dad for Christmas (the one that always wound up in the trash).
7. The Hacker. No, he has no interest in messing up your computer; he's too busy coughing and hacking and sneezing all over you. There is no escaping The Hacker. Bonus Points: Hacker also has a mysterious rash all over his body, but tells you, "I'm pretty sure it's not real contagious."
8. Typing/Texting Twit. You sit down, and boom! The elbows start flying, and you start hurting. Whether the moron next to you is typing or texting, it comes down to the same thing: bruises. The fun continues when you try to explain the discolorations to the spouse. Bonus Points: Twit finally puts away the phone and laptop -- only to pull out the PlayStation, to begin a zestful round of "NHL Hockey."
9. Snuggle Bunny. Snuggle's sin is fatigue. Fatigue and the inability to distinguish between your shoulder and a pillow. Snuggle will snore away the entire flight, in comfort -- on you. Bonus Points: Snuggle Bunny has a drooling problem.
10. Lavatory Lizard. Lizard is kin to Jack in the Box; he too hops up again and again, to head to the restroom. And without fail, Lizard urges you not to get up -- and then steps on your feet. Bonus Points: Whenever the flight attendant comes by, Lizard is the first to say, "Another water, please!"
11. Yellular. For some reason, this middle seater believes his cell phone is actually a megaphone; he may be sitting in row 29, but believe me, the pilot can hear him loud and clear. Yellular gets on the phone the minute he sits down and doesn't get off till wheels up -- regaling you, and everyone else with conversations like, "How is the cat doing? Still got them hairballs?" Bonus Points: You're stuck on the tarmac for three hours while Yellular is yakking away about his latest romantic adventures -- in excruciating detail.
... She must like the sound of her voice. 
on person next to us during take off!