My family has always called me Madyy since it's a shortened form of my real name.
One of my uncles has the tendency of calling me Maddog...because he knows I don't like it. XD
Back in the 7th grade, one of my older cousins (who was in the 8th grade...and he's a cousin long down the line) started calling me Matilda because apparently I look like the girl off the movie...I still get called that today by pretty much every black kid in school...my cousin hanged out with them a lot. I used to not like it, but it's grown on me.
Madeline...just a random name some people call me when they get bored with Madelyn
Madelyn with the Green Roof - long story...one of my friend's mom (who is the high school counselor) calls me this because when I was little, I lived in a house with a green roof and my friend could never remember my last name, so she called me Madelyn with the Green Roof.
Mark - an online nickname from a forum I'm active on (and used to be staff on...)...most of my friends on there (who are all guys, btw) had a girl nickname and I didn't keep my big mouth shut, so I ended up with a guy nickname.
Madyypoo - an online nickname from a friend from the forum mentioned above.
Madyygirl - an online nickname from another friend from the forum mentioned above
And I have a nickname from the same friend that calls me Madyygirl that I can't say on here...language, kids. XD