#3 makes me want to actually learn the words to Rebecca Black's Friday song.
I always pretend to mistake their yell or, since it's cold, honk for a "hello" and give them a friendly wave back. They never know quite what to make of it.
I wave, unless they have fully passed. Motorists ahead have mistaken a five-fingered wave for a nasty gesture. That is much less likely if I'm still ahead since they are looking at what they are yelling at.