Reddit reviews Window Marker - White (Temporary Paint for Car or Home Windows - Washes Off with Water)
We found 2 Reddit comments about Window Marker - White (Temporary Paint for Car or Home Windows - Washes Off with Water). Here are the top ones, ranked by their Reddit score.
Window Marker - White ColorSelf-Contained Sponge Tip Under Marker CapVolume: .84 fluid ounces (24 ml)Washes Off with WaterCap Indicates Color
Paint the lines on!
An alternative to a sticker is the painty-pens they use at garages to write on windows. It comes off really easy:
https://www.amazon.co.uk/Window-Marker-Temporary-Windows-Washes/dp/B00EC2D1J4
You could draw a big knob on their windscreen.