I generally go for the "accidental" exposure route: The shorts with wide legs that allow a nice view when seated, forgetting to zip up after using the bathroom, forgetting to close the blinds while naked at home. Stuff like that. I do sometimes go the more daring route - discreet car jacking (usually at night), finding a quiet place in a park to relieve a little stress, rubbing one out in the men's room (I'll usually take a stall for that). And then there's pulling it out at the gay bars when someone asks to see it, but I don't really think that counts.
Aside from that, I'm really more turned on by the idea that someone could
catch me then the idea of having someone actually
catch me. With the "accidental" exposures, people can look if they want, but it's not "in their faces" as it were; usually, if they want to look, they will, and if they don't, they'll pretend that they didn't see it because it looks, well, accidental
. The blatant "street corner flash" style, however, really forces people to look whether they want to or not. And the people who don't want to look generally get highly offended.
Of course, I do think that society is way too uptight about nudity in general and sex in particular, but as long as it remains so - and they are legal penalties for offending someone's delicate sensibilities
- it's best not to force one's self and one's penis on the masses. Give them the opportunity to look (discreetly), but don't shove it down their throats - unless, of course, they ask you to.