There seem to be a couple of variations on the s-shield. One of them is just the S, as Superman wears it. Another is an O, and the final one is the whole name, Obama. it seems to depend on the preference of whoever makes the image. And, of course, you can get the shield as a t-shirt.
And finally...It could all be true. Or a White House cover-up that will never allow us to know all the facts. You decide:
The White House has rigorously denied any involvement in the alteration of official photographs of the US president Barack Obama, which appeared to remove evidence that President Obama was wearing a Superman T-Shirt inder his white shirt. (courtesy of Newsifact)
I promise I'll get over my Superman-Obama obsession soon.