People are curious critters, you never know what they're going to do. With street photography there's usually not much chance of a do-over, so you just have to shoot first and try to figure out what's happening afterwards.
Sometimes you never figure it out. We'd went wandering in search of the only remaining United States Marine Hospital and found it hiding, half forgotten and neglected, behind some chain link fence. Still not sure why this dude was twirling a broomstick as he walked but I had to shoot him when he walked into my shot.
As we were walking back the last thing we were expecting to see was somebody selling cotton candy. The only thing in the direction they were heading was a few crumbling buildings, the interstate, and the Ohio River, so I still have questions as to who they were planning on selling it to.
Sometimes all you can do is shoot because they won't let you ask the questions. Does raise the question of 'if the news don't cover it, did it even happen?'
If a car cruises by and you take photos of it, does that count as a drive by shooting? Asking for a friend. The only problem with shooting first and asking questions later is that you end up with a bunch of photos and even more questions but not much in the way of answers.
C'est la vie. 
