Knock on Wood
DEFINITION: A superstition. You say "knock on wood" when you express pleasure at certain circumstances and hope they don't change.

EXAMPLE: Fortunately, I've never been in a car accident - knock on wood!
"Thank you very much! I would not have reached here [completing my dissertation] without your help."
Omana Simon
Candidate for Doctor of Nursing Practice
Michael E. DeBakey VA Medical Center, Houston, TX