|A bus in Playa del Carmen near where I live.|
If you've only ever been on a bus in Canada or the U.S., you'd have no idea of how much fun this can really be. Our favourite is "The seats on the bus go bump, bump, bump." The most fun is trying to sing, as the seats, the whole bus, and the people on it actually go "bump, bump, bump" so much that you have to hold onto something to stay in your seat, or at least avoid ending up on the floor.
In the small mini-buses (like in the picture) the morning and afternoon school rush often leaves us standing up in the middle; usually when there's an adult with a seat, they'll at least give the three-year-old a place to sit, but when everyone else has a 3,4 or 5 year old, or just no body is that thoughtful, we're left standing, him holding onto my leg, and me holding on the rail at the top, not being able to stand up straight because the bus is just too small. We still sing our song, though.
When my wife was going to fly for the first time (this was after we were married with our first baby, who is now the three-year-old), she was concerned that he wouldn't handle the flight well. I reassured her that if the baby survived the buses on Mexico City's old roads (where we lived at the time), the take off and landing would hardly be noticeable. I was right; our baby didn't cry.
I've been on the old buses running through the mountains in Greece, and they're even more fun. Mexico's old inter-city bus services used to be like that - both my dad, my wife, and many Mexicans I know experienced those buses - but they're now quickly being modernized, with soft, comfortable seats and movies; the old highways that were almost wide enough to avoid oncoming traffic, and really made the bus bump, are being replaced with wide, smooth, modern highways.
In the mean time, many of the city buses still go bump, bump, bump, enough to be fun, and give people with motion sickness a hard time. Singing helps.