Let's see...
"Stuff" - HATE it (still get it from my father all the time, and occasionally from my brother)
"Snuffleupagus" - Loved him, but hated the nickname
"Droopy" - Popular in high school because I was always so down or withdrawn (I never minded that one too much)
"Sam" - My fave (thanks DH)
My most common one is my shortened name (the first half of my real name). It absolutely never bothers me among family, but I always notice when others use it, and for some reason it feels a little too familiar when someone I barely know shortens my name like that. lol
"Gourd head" - Yeah, my head is not that freakin' big okay. But it still makes me laugh. (Thanks to DH again...)