Ghostbusters has many good quotes (e.g., no dick), but here's a few that I've actually used in conversation:
"Don't cross the streams"
"It would be bad"
"Yes, have some."
"I don't have any Tylenol, but I do have some acetylsalicylic acid."
"Listen... do you smell something?"
"Where do the stairs go?" "They go up"
The last one usually isn't quoted directly. Rather some variation, such as "I wonder what's behind that door." "A room."