n. 1. A protocol packet or item of email
(the latter is also called a letterbomb) that takes advantage
of misfeatures or security holes on the target system to do
untoward things.
2. Disapproving mail, esp. from a net.god,
pursuant to a violation of netiquette or a complaint about
failure to correct some mail- or news-transmission problem.
Compare
shitogram.
3. A status report from an unhappy, and probably
picky, customer.
"What'd Corporate say in today's nastygram?"
4. [deprecated] An error reply by mail from a daemon; in
particular, a bounce message.