Someone who is a total tool, but you cannot refer to them as a tool because they are your "friend" or you are related to them.
ME: I don't want to go to Scout's Bar Mitzvah.
MOM: Why not?
ME: Because he is a blue tool and I hope he dies soon.
A person who always has to bring you down when you are happy about something
A person who always says "for sure" when you make plans then squiggles out at the last minute
Me: This apple pie my mom made sure is delicious
Dude: I hope you are still saying that about apple pie after your mom dies.
Me: Thanks Cock-Dog.