There is a reason even for the most unusual customs we follow.
Have you ever seen an older religious Jew pull the Bottom of his ear after he sneezes? He probably doesn't know why, but there is a reason for this strange custom, too.
We are born head first, and when we die they slide us into the grave feet first. Before Yaakov Avinu people did not get sick. When their time to leave the world came, they sneezed and left.
So, the Chassid who is pulling the bottom of his ear after he sneezes is, so to speak, making sure that he has not left the world. To be sure, he is pulling the last part of his body that leaves, back into the world.