Oh don't lie. EVERYONE'S done the 'holding-it' dance. When you are at home and the lone bathroom is occupied and your bladder is mad as hell about it. When you are at a concert and the only options are the gross port-o-potties filled with cringing layers of other people who can't aim or the grass...if only defecating in the middle of the concert wasn't illegal. Or when you are watching Lord of the Rings again and are heading into hour three realizing that big gulp was probably not a good thing to drink before movie.
At least in those instances, you could go somewhere and try to relieve yourself. On the bus, it is worse. Ten times worse. What if you had a nice lunch. You knew the bus ride would be long, namely because the drivers go at a snail's pace. You made note to drink just enough to satisfy. You even went religiously to the bathroom to empty yourself so that this wouldn't happen. You think you possess a rather healthy bladder.
You do all these precautions, but then that horrible feeling arrives and that realization that you were wrong hits you as your traitorous bladder swishes with more fluid.
You've already been sitting on the bus for 30 minutes, crammed with strangers, some who may even feel your pain. Stop after stop you hold it, thinking "Oh, I can hold it, I'll wait." But in truth, you simply don't know the area enough to switch off the bus to use the facilities. You only pass through from home to work. You don't know if this place is full of criminals (pro tip: if you don't know the area, it probably is full of criminals).
Actually, your reason was more noble than that. That painful wiggle and knowing that getting off means spending more on a ticket. Spending more money you don't have, or more ironically spending change you don't have, as the rest of your non-existent bus allotted funds sit on your various pieces of plastic because we live post-2000 and everyone uses credit cards.
I hate the holding-it dance. The bus jerking around at every stop does NOT help.