If you're sitting around and thinking "Gee, I wish strangers would approach me in public and perform weird actions on me", then boy, have I got an iPhone app for you!
The app's called Situationist and it basically encourages you to upload a photo of yourself along with a list of appropriate things you want a stranger to do to you in public. Simple enough, right? Then all you have to do is wander around until someone who is using the same app spots you and picks an action off the list:
These situations vary from the friendly "Hug me for 5 seconds exactly" or "Compliment me on my haircut", to the subversive eg "Help me rouse everyone around us into revolutionary fervour and storm the nearest TV station". Members simply upload their photo and pick the situations they want to happen to them from a shortlist, in the knowledge that they might then occur anywhere, and at any time.
Situationist is free and available in the app store now. [iTunes]