Diabetes Card
Generating an excuse based on a a diabetes side-effect. The use of a diabetic card can (with varying degrees of success) cause a dropping of the original subject... often due to the other person's discomfort with the subject.

It is one of the few perks of a incurable disease which requires painful medical treatments multiple times daily and can shorten your lifespan by 15 years, cause blindness, kidney failure, liver problems, extensive nerve damage, and other terminal health problems. The truth of the "diabetic card" may vary, as with other excuses.
Professor/Teacher/Employer: "Why were you late this morning?"

Diabetes Card: "My blood sugar was 350 mg/dl last night, and I was unable to go to bed until well past 3 AM."

Professor/Teacher/Employer: "Ah... well, look out for yourself."