OKAY SO theres a flashback in the s4e24 episode of the pilot episode, in the barn when Ali slips the pills in the drink. This could be and probably is nothing BUT Alison gives Aria the drink and says ‘your turn’. Spencer then says “Careful area TAKE too much and you'll tell us all your secrets.” Who says take instead of drink? Who’s to say that they didn’t plan on taking a pill? Maybe Ali just gave them a different one. We don’t see the girls not looking when she’s putting it in the drink. We just get a close up of Ali putting it in. So it would still work out that Ali drugged them to see if one of them were A. The girls would still be surprised. For the Spencer already pill popping part - not all pills react badly with each other. She could have done previous research and decided that this one would be okay but then Alison gives them a different one and kablamo. Alison didn’t know yet that she was using. Just an incoherent thought but who knows anymore
