That would just be plain wrong.

All, of course, will not be plain sailing.

It'll be plain sailing from here on in.

I'm just gonna be plain old Billy, alright?

"Might makes right. As will be plain in sight."

I may be plain,but I'm not a fool.

How could he possibly be called plain?

You'll be just plain old Jenny Johnson.

Be plain, good son, and homely in thy drift. Riddling confession finds but riddling shrift.

His pleura's in fine condition. Should be plain sailing from here on.