I was once approached by the Police while eating fish and chips in my car with a mate.
At the time we were both in the T.A. Had been away with them the day before, and both had the day off. They asked to check in the boot, and that's when I rememberd that my kit was still in there....complete with a machete and knife attached to the pack. They asked what it was for, I told them, they said OK, then arrested us both as we matched the description of two chaps seen leaving a recently burgled house in the bottom of the village.
We were put in the Van and shipped off to the station before a quick detour to the house for the owner to confirm that it was not us they had seen and they let us go.
We could have been in all sorts of grief due to what was in the boot, without a valid reason, but common sense prevailed and they used their noddles. It was just an oversight by myself, and one I made sure not to repeat. I think they only arrested us in order to elliminate us from their enquiries (and possibly to get some of our chips)
Mind you, while the owner was looking in the van to ID us, it was the longest 10 seconds ever till they shook their head and said "No, that's not them"