In the States a guy who is interested in a girl has to work up the nerve to come up to her. A guy has to have the guts to face rejection to get a chance. Just whistling at her or yelling "Que bonita" (how pretty) would not work, in fact it would likely work against him. Here in Panama whistling, hissing, and calling out piropos (spanish for calling out comments or compliments at a woman) is normal.
To my ear it sounds rude, like annoying bored construction workers, I would never pay attention. In fact there are times when I swear the next guy to say something will get the best earful of Spanish I can muster and I walk along practicing a good stinger to give. But here piropos are how a girl knows when a guy is interested...they say that it tells them that they are pretty.
In the USA when we are walking along a sidewalk side by side and someone approaches us from the other direction we automatically yeild some space by merging into single file. I wasn't even concious of this action until I got to Panamanian side walks (which are challenging just as sidewalks). In Panama they do yeild...but only the minimal necessary. They will not merge into single file...they just wait until that last possible moment to squish down to let you pass.
Every time it happens to me I swear that this is going to be the time they bump me off the sidewalk...but it is rare that thier bags even brush me. This felt unbelievably rude to me when I arrived, but now I realize that it is just the way things are done here. They don't run into each other...they just seem to have a different (smaller/closer) cultural norm on personal space needed for passing others. I still don't feel comfortable in those passing moments, but I have come to realize it is because I carry a different cultural expectaition from the norm here.
I have more cultural contrasts to offer...but I need to go catch a bus home. Take care on the sidewalks out there.