Vampire References?

[Megan]

No: HPFGUIDX 28634

I'm sure I might get myself in trouble here (hehe), but what exactly
ARE the "vampire references" some people thinking refer to Snape's
un-dead status?  I've personally never noticed any myself and have
thought any references to Snape being a vampire were purely
fanfictional.  But obviously it's a subscribed-to theory...so, clue me in?

-Megan (who firmly believes Snape is quite alive [unfortunately])