Use this one:

report.jpg

For example: if you see bad post, bad language using an so on, or spam or flood or promotion insulting the other members, or commercial signature and so on - press this report button. And your message will directly go to admins' email.
Admins/moderators understand those reports as official reports and must take those reports onto consideration.

Please note - it is just about one post ony: report button corresponded to the bad post. If one member did 5 bad posts so use 5 buttons and member will get 5 reported posts (it is exceptional case for the member to have 5 reported posts as the member will be banned on 3rd or 4th case) - and thi member will not know about who reported against him to be banned as decision about banning is taken by admin/moderator (not the member who reported).