Aria: "If you're about to tell me a flashback where you saw Ali's ghost and forgot to tell us about it, I swear to God."
Mona has decorated the kitchen with a million candles, fittingly enough for a séance. This is before Alison's body was discovered, back when death was imaginary and a thing that happens to old people, so it wasn't quite as gruesome as it seems. Unless Mona knew Ali was dead, of course, which knowing Mona...
Mona: "I know it seems stupid, but I totally have talked to ghosts. Knowledgeable ones, as recently as this summer. Let's do this. Secrets of the universe."
Hanna: "This is weird and dumb and the opposite of what I'm into."
Mona: "Just do it! I am your only friend! Why are you challenging me?"
Hanna: "Fine. Ask the spirits if Sean is a virgin."
Mona: "Something we don't already know the answer to! Let's ask if Ali's ever coming back."
Hanna: "That's macabre in the extreme, mon amie."
Ouija Board: "A-L-I..."
Hanna: "I know, Ouija Board! That's what we're asking!"
Ouija Board: "A-H-E-M."
Ouija Board: "A-L-I... V-E!"
And how does it know? Oh, just because Alison is plainly standing outside the French doors onto the back patio, just chilling. Practically gives a little wave. NBD.
Aria: "Um, I'm not even going to address the ghost part, but remember how Mona was already A by that time?"
Hanna: "Whatever. This evidence in a murder investigation is going in the trash. Just like Spencer would tell us to do."
Aria: "Okay, but who else would know that story? Just Mona, right? So she told A about it, at least..."
Hanna: "Yeah, I've done everything short of calling in a bomb threat to make sure they don't let me back in there."
Aria: "Then I shall go, Hanna. I shall go, and I shall be victorious."
A random flowerpot is hurled at the backdoor, and never mentioned again.
Hanna, verbatim: "...So I'm sleeping at your house tonight."
Aria, verbatim: "Yep."
Spencer: "Hey, Jason. What's up?"
Jason: "Just jogging past this high school half-naked. As a former Peeping Tom, I like to just keep my hand in."
Spencer: "Hey, are you going totally nuts by how we embarrassed ourselves by contributing to justice?"