A longer phrase than fuck my life but means the same thing. Usually used after something very bad happens or someone says something bad. Can be followed by putting your index finger and middle finger in your mouth and moving your thumb..like your shooting yourself.
Girl 1: What would you do if I broke your dick in two pieces.
Guy 1: Click boom splat thump.
Girl 1: Same here!
Sales Theory - When sales volumes rapidly increase for a period of time and then splat down.
Jason was looking for a great way to sandbag his budget so he came up with the Boom-Splat sales theory.