Whom Shall I Say Is Calling?

The usage of whom is "devilishly complicated," so people either don't use it where it is appropriate or use it where it is inappropriate. Thus, most people ignore it and just use "who" for everything. I must say, I'm sympathetic to this; I personally only use "whom" when there's a preposition before it, 'cause that's the only time I'm totally sure it's correct.

(Via Bookninja)