Oatmeal: Who and Whom

I'm sure many of you are familiar with the fabulous comics at TheOatmeal.com, including the series of Grammar posters. One of them is about who/whom, which is not a grammatical distinction that I worry about most of the time (poor "whom" is on its way out, alas... even in sentences like the one below), but if you do want to make sure you use who and whom correctly, the Oatmeal poster provides a hilarious tutorial. This is just one item from the poster which you can see at The Oatmeal site.