It's photoshoped. Maybe not by photoshop(TM), but it's been altered. There are some 'fonts' out there that do vary the letters. Also, I've seen that very same picture before with different captions. One involved the same saying, but for John Kerry.
The crease through the USMC is probably origional, but if you look closely, there is a crease around the --, but they aren't affected. The -- also look thin for a marker.
And I agree with it!
Oh, and Michigander, I think your pic is photoshoped too.