Do what I did on my first ever major crash.
Plow right into them.
Worked for me - except for that whole over-the-handlebars thing.

I was also on the other end of this situation my freshman year in Boston.
All wided-eyed and innocent and I walked into the street and right in front of an oncoming cyclists.
He was able to slow down a fair amount but there still was a little bit of a crash.
He seemed pretty pissed and I was super embarrassed.