Sis code

The following guys are excluded from the list of datable guys

1) ex (all types of ex's)
If you broke up with him once, there must had been a reason there. You might not remember. You might want to forget the reason. Or you might not understand it...
... but be aware that sooner or later that reason will arise again and again. And by then it will be still THE reason to motivate a break up.

2) Boyfriends of your friends
For the obvious reasons: if you don't mind to loose a friend due to such a selfish behavior, look at the guy and think that he might do the same to you sooner or later.

3) Ex-boyfriends of your friends
You don't want to put your friends into an occurred situation, do you? And think careful, if she is really your friend, wouldn't you be suspicious about the reason that they are not together anymore?

4) Boyfriends of a good friend of a good friend
Let's spare your good friend some headaches, OK?

5) Guys on exchange stays or about to leave for it
You don't a "Lover with a love in each harbor". These are the typical fuckable guys (however should be regarded as a distinguish case from the Fines).