[quote name='botticus']If the punchline didn't involve kids under the age of 12, I guess it would be more amusing.[/QUOTE]
On first reading, without being aware of the situation, I got this scenario: Teacher was going to make kids dress in traditional South American garb and did a search to get ideas. Their first hits were probably the scantily clad pictures in the email and they thought sarcastically, "Oh yeah, the kids would look *great* in those outfits." Then out of amusement or perhaps even disappointed that those were considered traditional South American garb, forwarded their sarcastic remark along with the pics.
Either that or they're into little kids.
I personally know more sarcastic teachers than I do child molesting teachers.