A feline litter usually consists of two to five kittens born after a gestation lasting between 64 and 67 days, with an average length of 66 days. Kittens emerge in a sac called the amnion, which is bitten off and eaten by the mother cat.
Harley Quinn. Dr. Harleen Francis Quinzel, also known as Harley Quinn AND is a 'VILLAIN' not 'ANTI-HERO', first appeared in the Batman: The Animated Series episode Jokers Favor (episode #022, original air date: September 11, 1992) where she served as a humorous female sidekick to the Joker.
Then again, apparently, it was a tribute to Jack Nicholson and Alan Napier, according to the DC Wiki Article: Jack Napier is an alter-ego associated with the Joker. In Tim Burton's 1989 film Batman, it was used as the character's real name. This is a tribute to the actors Jack Nicholson and Alan Napier. Since then it has been used by several other incarnations of the Joker, although usually as an alias and not a secret identity.