It's rude to avoid people.
John is walking down the street when he spots an old acquaintance, Dan walking towards him and waving at John.
John wants to respond to Dan's wave.
John waves back at Dan and tells Dan hello and that it's been a long time so it's nice to see him.
John quickly looks down at the ground pretending not to notice Dan's wave and scurries off in a different direction.
Dan is happy at John's polite statement and is happy to see a familiar face in the crowd.
Dan is hurt that John is seemingly trying to ditch him and wonders what is wrong with him that John would not want to talk to him.