There is still no cure for the common birthday.

Glenn’s quip treats aging as an unavoidable, universal condition—something like a “common cold” that afflicts everyone on schedule. By calling it the “common birthday,” he reframes getting older as ordinary rather than tragic, using humor to deflate anxiety about age and mortality. The line also fits Glenn’s public persona as someone who repeatedly tested physical limits (combat pilot, astronaut, later returning to space at 77) yet acknowledged that time remains undefeated. The joke’s sting is gentle: you can postpone, deny, or out-achieve many things, but you can’t opt out of birthdays.