What's the appropriate Unicode character to flag users on the website?

I run a quiz-like website at slagalica.tv (content is not in English). We often have users that try to cheat the system, so we flag those accounts and they get special treatment. Now I'd like to add some character beside their name to be visible everywhere across the website, so that everyone knows those accounts are flagged.

I'm currently considering to use the "dagger" character

http://en.wikipedia.org/wiki/Dagger_(typography)

which is used for different purposes in different domains. But I fear that I do not know about some cool Unicode character that would fit this purpose better.

Any ideas?

From stackoverflow

• What about Skull & CrossBones?

  ☠

  Some other possibles at: http://www.alanwood.net/unicode/miscellaneous_symbols.html

  Wez : Good call hehe! Also add a ALT tag to the symbol so they see an informative tooltip what it means.

  Milan Babuškov : How do I add ALT tag to text?

  Matt Lacey : ALT only applies to images. Wrap it in a span with a title to get the tooltip effect.