Was gonna comment on the original topic, but what the— Abbreviations gone awry o_O And this is why you should avoid abbreviations except for a few well-estabilished ones...

As for the original topic, I find this a lot (and yes, with basic types, not classes which could have side-effects):

if (!blah)
   blah = true;

This could have easily done the job:

blah = true;

Unless it is dynamically typed language (like javascript):

var blah = "hello";
if (!blah)
    blah = true;

// blah remains "hello"

blah = 15;
if (!blah)
    blah = true;

// blah remains 15

blah = 0;
if (!blah)
    blah = true;

// blah is true 

I hate dynamically typed languages for allowing this.