If I'm desperate I will get out and chuck a couple of handfuls of snow at the windies ... this is usually sufficient to get them clear enough to drive on ... I have seen occasions where I have used one of those "sports" bottles with the drinking nozzle to squirt water from the driving seat (usually coz some silly sod used water or diluted windscreen wash during winter to top up the washer bottle ... I always used the undiluted stuff during the winter months in my Unit and in my own vehicles.)
Sadly, this year I have been caught out ... The last time I topped up my washer bottle was about a month ago and I have used next to nothing from it since, therefore I need to try and empty it by excessive use so I can get some squoosh juice in, I think it's gonna be a cold winter this year, this is only December and it's beginning to get a bit fresh out there already ... Christ, one day last week I had to put on a long sleeved tee-shirt to go shopping, my arms were getting cold wi' the short sleeves I normally wear.