I don't think that exhibitions at street fairs, such as Dore, Folsom, Decadence, pride festivals, etc., really qualify as outlandish public displays of affection. The reason is that these events are not truly public, but rather are events where like-minded people gather specifically for the purpose of demonstrating their sexuality, liberation, and self-pride. Although they take place on public streets, these events are really more in the vein of vast private parties. Although anyone may attend, the great majority of the crowd is composed of people that would approve of, or at least not be offended by, even quite blatant displays. Such displays as I have made at the aforementioned events were hardly intended to be affectionate. Rather, they were intended to be exhibitionist, for entertainment of the crowd, and generally involved partners for which I had no particular feelings.
I believe true public displays of affection occur in mixed everyday situations, like main street on a non-festival day, or in various other public spaces where there is no sexual themed event in progress. Probably the most blatant such display I've made was on a BART train, packed full of morning commuters. After some fooling around in the corner of the train station, I rode all the way from Market St. to downtown Berkeley with a guy sitting on my lap and vigorously sucking face the whole way, with just a bit of mild groping, too. I actually liked him, and my intent was not to be an exhibitionist, but to deal with my affectionate feelings. I bumped into him twice more later that year, at the Dore and Folsom fairs. We did make a public exhibit at Dore, which I guess attracted attention, as I've seen a picture of me holding him with one arm, with a big wad of his cum in my other hand. However, I consider what we did on the train to be much more of a PDA than what we did at Dore. (To finish the story, I fucked him at Folsom, but in my hotel room, not the street.)