I was walking up the main road from work to the bus stop, passed under an overhanging tree, and suddenly there was all this fluid in my face. I started to wipe it off, thinking it was from the tree (you know how, when it rains, trees can store up quite a lot of water to be unceremoniously dumped on you later?). Looked round at the car that was passing, wondering how it had managed to splash water from the road up into my face. I carried on walking and wiping my face - then I realised it was vinegar from the smell.
I'm just angry that I fought the initial impulse to memorise & write down the car's registration number because I thought it was an accident. Had I written down the number and it was an accident, I could have just thrown the piece of paper away - but as it is, I'm missing the one useful piece of information I could pass onto the police. And the vinegar solution was strong enough that by the time I got home (about 15 minutes later) my face was actually stinging. Vinegar is an acid - admittedly, not very strong - but if someone's driving around squirting vinegar into strangers' faces, who knows if they'll graduate to something more actively noxious?