I think you guys are getting me mixed up. I'll try and clarify:

1) Right now all available quests are marked on your map...AND
2) Once you start a quest there are markers and highlighted areas showing you where to go.

The exception to this rule is the "Greatest Secret" quest. This quest is:

1) Marked as an available quest on your map...BUT
2) Once accepted there are no markers or highlighted areas to show you where to go.

What I am asking for is:
1) A quest that is NOT marked as available on your map...BUT
2) Once accepted, there are markers and highlighted areas to show you where to go.

I am NOT asking for:
1) A quest that is not marked as available on your map...AND
2) Once accepted, there are no markers and highlighted areas to show you where to go.

The only "secret" part is obtaining the quest. Some people will just look up everything online, but I think there are a large amount of players (like myself) who will be more than happy to stumble across it accidentally.

P.S. That comic is funny