Did it in the stall in a McDonald's once, when I got desperate. My brother did it once in the parking lot of a grocery store, just reached into his briefs... broad daylight, too. Almost got caught when mom came back, oops.
I've done it a couple times while driving, that was pretty cool.... it's a good way to pass the time on long drives cross-country. Once I was driving along at like 2 in the morning, out in the middle of nowhere.... stopped to pull off my pants, so I was driving along in my boxers, jacking off for an hour or so (I love edging). Pulled over and stopped in an open field near an overpass or something, dropped my boxers and lay down in the middle of it to finish up. Planted some nice seed for that farmer
Urinals are overrated, unless they're clean... been there, done that too.
On a bus? Once, back in college.... going off to visit relatives for the holidays. I was a little too chicken to pull it out, so I rubbed it through my pants (got to a good bit of the book I was reading). There was another guy in the seat across the aisle, I'm pretty sure he caught me... kept smirking at me the rest of the trip, asked "good ride?" when I got off (the bus, that is).