Inviting yourself is bad.

src/main/java/com/gmail/nossr50/party/commands/PartyInviteCommand.java

@@ -46,6 +46,11 @@ public class PartyInviteCommand implements CommandExecutor {
             mcMMOPlayer = Users.getPlayer((Player) sender);
             player = mcMMOPlayer.getPlayer();
 
+            if (player.equals(target)) {
+                sender.sendMessage(LocaleLoader.getString("Party.Invite.Self"));
+                return true;
+            }
+
             if (PartyManager.inSameParty(player, target)) {
                 sender.sendMessage(LocaleLoader.getString("Party.Player.InSameParty", target.getName()));
                 return true;

src/main/resources/locale/locale_en_US.properties

@@ -520,6 +520,7 @@ Party.InformedOnJoin={0} [[GREEN]]has joined your party
 Party.InformedOnQuit={0} [[GREEN]]has left your party
 Party.InformedOnNameChange=[[GOLD]]{0} [[GREEN]]has set the party name to [[WHITE]]{1}
 Party.InvalidName=[[DARK_RED]]That is not a valid party name.
+Party.Invite.Self=[[RED]]You can't invite yourself!
 Party.IsLocked=[[RED]]This party is already locked!
 Party.IsntLocked=[[RED]]This party is not locked!
 Party.Locked=[[RED]]Party is locked, only party leader may invite.