Originally Posted by
mstraus
Isn't that what the soft back of the thumb on your bike gloves is for?

Other option is the snot rocket.
On a more serious note - Never assume
1) you know what a driver will do
2) that a driver sees you
If you keep a defensive mindset it may help you avoid an accident caused by a careless driver.
Lies. You always know that the driver (A) sees you and (B) is trying to hit you and make it look like an accident. If they slow down to let you go, they are really only trying to coax you out in front of them. You must have an escape route at all times.
Also, if there are cars parked on the side of the road right next to a lane labeled “BIKE LANE”, someone made a mistake. It should be labeled “DOOR ZONE”. Do not ride there unless you want to hit a door as it opens.