In his book, Dan Ariely talks about our tendency to be dishonest when we're in a tough spot. John Ortberg expounds on it in his book, Soul Keeping:

Ariely's book clearly gives empirical verification for what you and I know happens all the time. Here is a tiny example I hope you cannot relate to: Ariely says, "Over the course of many years of teaching, I have noticed that there typically seems to be a rash of deaths among students' relatives at the end of the semester. It happens mostly in the week before final exams and before papers are due." Guess which relative most often dies? Grandma. I am not making this stuff up.

[Another research study] has shown that grandmothers are ten times more likely to die before a midterm and nineteen times more likely to die before a final exam. Worse, grandmothers of students who are not doing well in class are at even higher risk. Students who are failing are fifty times more likely to lose Grandma than non-failing students. It turns out that the greatest predictor of mortality among senior citizens in our day ends up being their grandchildren's GPAs. The moral of all this is, if you are a grandparent, do not let your grandchild go to college. It'll kill you, especially if he or she is intellectually challenged.