Knock back a beverage of your choice every time...
Someone staggers down a corridor covered in blood.
Someone wounded is carried down a corridor.
Someone stalks down a corridor with their gun at the ready.
Someone slumps despondently on the floor, their back against a door (extra swig if in a corridor).
Someone has the top of their skull removed.
Somebody stares vacantly into the middle-distance to signify that there’s a flashback coming.
Someone is splattered with somebody else’s blood.