Explosive Material?

So the other day, I was at some place on campus when I saw an amazingly confusing T shirt.  There was this girl standing next to me who, well, she was big.  She was about 6'1" and very overweight.  I usually would ignore a fact like that, but it kind of adds to the mystery behind her shirt.

On the front of the shirt was the word "Boom."  On the back was "Caution: Explosive Material Inside This Shirt!"  Hmmm... Let's just take a minute to take that in.  I just don't know what that could possibly in reference too.  Is she a suicide bomber?  Is she wearing a large body suit filled with dynamite that just makes her look fat?  I just can't figure out what message she was possibly trying to convey with that shirt. 

Like I can usually appreciate an ironic shirt or a shirt with a funny saying like:

Her shirt just wasn't doing it for me.  I was to tempted to just lift her shirt up and take a peak at what was happening in there.  I didn't.  Because, well, I think that's sexual assault.  But more importantly because I feared what I would find.  Either it was a bomb, and I was about to die.  Or it would just be fat, and then I would just want to die.  Either way, nothing good could come out of it, except for an explanation for the shirt. 

Has anyone seen this shirt before?  If so I'd love to know what the circumstances were.  Was that person wearing it also obese?  If so, maybe this is just their way of announcing to us some new scientific breakthrough in which they are revealing to us that fat is explosive.  It seems a little convoluted though.  They could just make an announcement in the press or in a science journal, you know?  I dunno.  Maybe I'm just out of touch with explosive fashion.