“We all knew Larry [David] was a hypochondriac… Lenny [Maxwell] was given a book on the theory of type A and B personalities and their correlation to heart attacks. On the inside cover, pretending to be the author, Lenny wrote an inscription that said he had seen Larry’s set at the Improvisation, and it was obvious that Larry was both type A and type B, and that he should seek medical attention immediately — he was a ticking time bomb. We mailed the book to LD.
A few nights later Lenny and I were sitting at the Improv bar when the door burst open… Larry ran up to us, holding the book, his hands unable to contain the tremor, practically stuttering, ‘Uh… I got this book in the mail.’ His unsteady fingers poked at the page Lenny had written. ‘The doctor saw my act. I’m going to have a heart attack!'”
-Comedian John DeBellis, a former writer for Saturday Night Live and Politically Incorrect, writing for HuffPo about a time he and a friend pranked a young(ish) Larry David into thinking he was going to have a heart attack in the late ’70s.