What does Backblast Area Clear mean?

Backblast Area Clear meaning in Urban Dictionary

a. a military cautionary statement, when you're firing the AT-4. One looks behind them, checking for employees 100 meters back a 90 degree cone, as soon as it's clear they yell backblast location clear and fire. b. One seems to their rear, and whether it's clear or perhaps not, yells BACKBLAST LOCATION EVIDENT, and rips a loud veracious fart.