Most men, in their final moments, turn to God, making amends for past transgressions. Others grab the nearest nurse, write out a makeshift will, or spend what little time they have left confessing admiration to those around them.
Told of the possible destruction of the 4077th, and therefore his possible untimely death, Hawkeye spent his predicted last few moments in a way only he could.
When the camp realized their lives were out of danger, Hawkeye's pranks of an exploding latrine, snakes in every bed, underwear up the flagpole, and shoes filled with cottage cheese suddenly didn't seem so funny.