Quote Originally Posted by thescot View Post
Well, there is that grammar thing, you know, matching the pronoun to its antecedent.

Everyone and everybody is singular, but their is plural. MOst people don't care, but some do. (Like English teachers.)

But as matter of fact, on a tee-shirt, I'd go with everybody. Just sounds friendly.
As another English teacher, I'll have to agree with thescot: concord is essential.

As well as being friendlier with everybody, I think "body" works well as a physical description linked to what is beneath the t-shirt.

Speaking of.... what did the German police officer say to his chest?

You are unter avest!