A 50/50 chance would be random(1), where the out come would be either 0, or 1.
So if random(1) equals 0 do this,
and random(1) equals 1 do that.
Note each time you do a comparison using random it will generate a new number. If you want to choose from one "roll" you will need to save the out put to a variable first, and then compare the variable is = 1, or 0.