Easy....because big brothers are just jerks, plain and simple.
'cause they r just plain mean!
you are just plain mean
The Wright brothers
That is just plain mean.
no. He just cared about his brothers.
The Wright Flyer
Perhaps you mean "conjectural" which means based on supposition, conjecture, or just plain guesswork.
It means what it sounds like. Or it can mean just plain and simply to kill said person.
Well, it means that your gums have teeth coming through and are itchy, your gums are just plain itchy and maybe swollen and sore, or your just plain wierd.
the Wright Flyer
It means loitering or socializing, or just plain "chillaxing."
If you mean just a plain game called "Star Wars" not to my knowledge.