Couldn't you tell after the first bite?

 You may not be able to read this, but this photo came along with a warning email sent to all the parents from school.  Apparently this is a popular Valentine.  And despite the prominently displayed caution on the front (DO NOT EAT), kids are popping these like candy. 

They're window clings.

I'm not going to make any comments about survival of the fittest... but....