Beryl: Paranormal? Is that what they're calling your kind these days?
Otho: Don't mind her. She's still upset because somebody dropped a house on her sister.
Barbara: We're very unhappy.
Juno: What did you expect? You're dead.
Beetlejuice: I'm the ghost with the most, babe.
[Beetlejuice angrily kicks a model tree and it falls over.]
Beetlejuice: Nice fucking model!
Adam: This book reads like stereo instructions. Listen to this. Geographical and temporal perimeters. Functional perimeters vary from manifestation to manifestation.
Bernard: Delia, you are a flake. You have always been a flake. If you insist on frightening people, do it with your sculpture.
Beetlejuice: It's showtime.
Adam Maitland: What are your qualifications?
Beetlejuice: Ah, well, I attended Juliard, I graduated from Harvard Business School, I travel quite extensively, I lived through the Black Plague and I had a pretty good time during that, I've seen The Exorcist about 167 times and it keeps getting funnier every single time I see it, not to mention the fact that you're talking to a dead guy! NOW WHAT DO YOU THINK?
Beetlejuice: Alright, let's get down to business! I got a card around here somewhere. Here, here, who do I have to kill? Here, hold that for me, would you?
Barbara Maitland: Whoa! Ah!
Beetlejuice: There you go!
Adam Maitland: You don't have to kill anybody!
Beetlejuice: Ah! Possession! Good! [Beetlejuice's voice comes out of Barbra's mouth] Learn to throw your voice. Fool your friends! Fun at parties!
Chosen answer: Barbara did conjure him earlier in the movie when she saw lights in the model going off and then said his name three times. According to Juno, they let Beetlejuice out but didn't put him back, which gave him the opportunity to attack the Deetzs.