1) A popular girl's name.
2) A slang term to refer to LSD (
lysergic acid diethylamide). The term "Alice" comes from the movie "Alice in
Wonderland" which is very popular among users of hallucinogens.
Alice is often used as a code word for LSD when referring to the drug in a public setting or over the phone where one does not want to openly discuss illegal activities.
Alice is used like a person's name in such discussions. Like saying "Alice is here, you
wanna hang out?" to indicate you have some LSD and want someone to trip with.