Just for fun, I typed "stupid bumper sticker" into Google Images. It turned up a lot of images used in blog posts, but sadly the posts are stupid more often than the bumper stickers themselves.
Here's a prime example: http://godsnotwheregodsnot.blogspot.com/2007/11/whom-would-jesus-vote-for-what-are-you.html
Note the bumper sticker "Whom Would Jesus Vote For?" -- I'm astounded that anybody would try and and sound all grammatically correct using "whom" for a religious bumper sticker. Which is twice as odd in that it's wrong. "Who Would Jesus Vote For?" is correct. Jesus would vote for whom? For whom would Jesus vote? Who would Jesus vote for? If you vote the way Jesus votes, who would you vote for? For whom would you vote if you voted as Jesus would vote? -- 'Whom' is an object. 'Who' is a subject. Trying to sound all smart with the message made them wrong... go figure.
Umm... no, actually. Grammar doesn't work that way. "Whom would Jesus vote for" sounds a bit awkward, but it is in fact grammatically correct. Separating "for" and "whom" does not change the fact that "whom" is the object of "for", and certainly does NOT make "whom" into a SUBJECT, even though it's been placed before the verb. The subject of the sentence is "Jesus"; he's the one performing the action (voting). If the sentence were "Who would vote for Jesus", then yes, "who" would be the subject.
I'm surprised the guy didn't try to argue against ending the sentence with a preposition (which, in English, there's no rule against, despite what a lot of people seem to think).