Almost a decade ago, while studying art, I built my own camera from an old document scanner, a big cardboard box and a magnifying glass, Michael Golembewski style. Basically, it was a big box with wires coming out of it, connected to a small laptop.

Now, because of the way a document scanner works you can make really funny pictures with this camera if things in the picture move while you "scan in" a photo. So I figured it might lead to interesting picture sif you take this camera, put it on a pram and then sloooowly walk back and forth through the street while scanning in a photo. A pram... with a big box... with wires coming out. TOTES INCONSPICUOUS.

Eventually three cops show up. Two are quite young, one is a bit older. The young ones are friendly and ask me politely what I'm doing, explaining that they received phone calls by concerned citizens about a suspicious looking guy (I'm a fairly tanned half-Asian with a beard and moustache, which is non-white enough to be "suspicious" I guess) walking back and forth in the same street with a weird contraption. I show them my ID and explain that I'm an art student and that that thing I'm pushing around is a home-made camera. The old guy starts talking in an accusational tone, asking why I can't use a normal camera, why I insist on being different, etc... so the two young guys, visibly embarrassed, send him away and deal with the situation in a calm, friendly manner ("could you somehow make more clear that this is a harmless activity, especially around the central station area?" - which is a fair request).

That's the least-nice experience I've ever had with police in this country (in terms of police not being nice, I mean; getting fined for driving a bike without lights sucks more, but as long as you admit that you're in the wrong they don't make a big deal out of it beyond "it's for your own safety! Now walk the rest of the way.").