Buffy the Vampire Slayer

Buffy: Early to bed, early to rise, balanced breakfast, hospital corners. It's a new beginning. Buffy's line is an adaptation of the popular aphorism found in Benjamin Franklin's (1706 - 1790) "Poor Richard's Almanac" that goes, "Early to bed and early to rise makes a man healthy, wealthy, and wise." Franklin is famous for his multi-layered talents and contribution to early colonial America. He was an author, diplomat, inventor, physicist, politician, and printer. "Hospital corners" refers to a method of making beds with neatly folded corners. It's commonly used in hospitals (hence the name) and in the military.

Willow: Kali, Hera, Kronos, Tonic
Air like nectar
Thick as onyx
Cassiel by your second star...
Kali is the Hindu goddess of destruction and death. Hera is the Queen of the Greek gods and the wife and sister of Zeus, the king of the Greek gods. Kronos was the previous king of the gods, dethroned by his son Zeus. Cassiel is the angel of temperance and good fortune.

Doctor Guy: I don't care if you ate too many Twinkies.

In 1978 Dan White murdered San Fransisco mayor George Moscone and his gay assistant Harvey Milk for reasons that included homophobia and the fact that his position had just been eliminated. During his murder trial his attorney argued that White's excessive consumption of junk food and his disinterest in exercise was a sign of depression that lead to the murder. This is the stimulus for the "Twinkie Defense". White was found not guilty of murder but convicted for (the less serious offense) voluntary manslaughter. He later committed suicide. This was the first of many stunt legal defenses before O.J. and Johnny Cochran.

Willow: Yeah, but not in a 'Miss Minchin's Select Seminary for Girls' way.
In the children's book A Little Princess written by Frances Hodgson Burnett, Miss Minchin's Select Seminary for Young Ladies is a Victorian school strictly ruled by Miss Minchin. The novel has been adapted for the big screen several times, most recently in 1995 starring Eleanor Bron as Miss Minchin.

Willow: I know what a Freudian slip is.
Sigmund Freud (1856-1939) was an Austrian doctor who is considered to be the father of modern psychiatric medicine. He forged the idea that would eventually become psychoanalysis: the idea that neurotic behavior is motivated by unconscious desires that can be revealed through such things as dreams or slips of the tongue. In Freud's theory, a slip is the involuntary substitution of a word by another and would be indicative of the real opinion and feeling of the person who makes the mistake.

Xander: It's Dawn Giovanni and the Buffster.
Xander's play on Dawn's name is a reference to Don Giovanni, the opera composed by Mozart which was first performed in Prague on 29th October 1787