When you walk up to someone on the sidewalk and you both try to move out of each other's way, and in doing so repeatedly move into each other's way. 

当你在人行道与对面的行人迎面遇上时，你们双方都试图避开对方，但却总是恰好又挡住对方的路。

例句： 

"Why are you late?"

"I got stuck doing the sidewalk salsa."

“为什么你迟到了？” 

“我遇上了‘人行道萨尔萨’。”