I just want to be clear. The temple garb is sacred like bigb said and is something not to ever be worn or shown in public?
Sort of, depending on what you mean. They are called temple garments because they are symbolic of sacred covenants made in the temple, not because we wear them only in the temple. But yes, they are considered sacred and not to be displayed. Clothing worn over the garments is supposed to cover them completely.
As has been mentioned before, mormons are heavily indoctrinated as to the sacredness and specialness of temple garments. They (we, I should say... I am an active, garment wearing mormon), as a group, can be very defensive about them.
Personally, I'm not. They're sacred, not secret. If someone else wants to use that angle try to be disrespectful, well, that's their prerogative. I can choose not to be offended. Hard core Morms find it difficult because they don't seem to understand that other people don't hold their underwear in the same high regard.
Like I said, I'm a Morm, and to this point I still wear mine, even though I am a horrible Mormon. But I often think it's a pretty cozy little scheme, telling members "You have to wear a certain type of underwear and, oh, by the way, we're the only supplier."
Posting (and re-posting) the pic was a deliberate attempt to rile the you-know-whos. And it worked. So, mission accomplished, right Alt?