nick dirt,
If you were playing a joke...then you were breaking no laws. It is not against the law to wear a hardhat or carry a pickaxe or shovel into any local public park that I know of. It may become an illegal act if you actually use them for their intended purpose [you may be perceived as destroying public property]. However, the police would probably have cited you destroying public property if they felt like they could have made their case. They should probably have said 'do not destroy public property while playing your joke'...so "pretending we were american diggers" should have been no problem. If the police didn't get the joke, they probably have seen the show.
As for me, yes...public perception is important for our hobby. But, when I encounter some overzealous idiot (yes, they're everywhere) that just doesn't like me metal detecting, then I go about my business of ignoring them and trying to avoid them. When and if the authorities show up, I show them what I'm doing and ask them if I am breaking any laws. If they say no, I tell them "have a nice day". Of course, they generally ask if I will just move on and I usually accommodate them.
Personally, I would never want to emulate American Diggers for any reason. IMHO, they're not funny, they're not entertaining, they're not realistic, they're not honest, they're just idiotic & obnoxious. Yes, there are overzealous idiots on TV too...and also in elected positions (but that's another topic)!!!
This thread should probably be in the Views Forum.