Die in an accident (especially a plane or boat crash) or be killed. From pilot slang, "gravity can ruin your whole day".
One tactical nuke can ruin your whole day.

Poor guy. He was trying to climb over a mountain pass when his engine quit. Didn't have enough altitude to make the turn. Ruined his whole day.
by s%mebody October 05, 2012
Get the merch
Get the ruin your whole day neck gaiter and mug.