Nicknames! :D

I have some pretty weird nick names some of them just confuse me:
Narwhal(My steam name used to have Narwhal in it, and some of my good friends still call me it)
Mysterious Pony(This came from a joke when I was playing Fallout 3 with one of my friends and we started discussing My Little Pony at the same time XD)
Tom (Tom isn't my actual name and a lot of people think it is on this forum but it is not, my actual name is Dawson. I just randomly pick names for my video characters)
Sandwich Killer(I stepped on one of my friend's sandwiches once and now he kills me this occasionally XD)