Invite all my whovian friends over for a party, put on the strobe lights, put on weeping angel costume.
Better prank idea: shove ice cream sticks in horse scat, freeze said faeces, give them to preschoolers telling them it's ice cream. Has been proven to work.
Better prank. Sleepover, draw tally marks on their faces while they're sleeping. Also, I thought you hated fandoms. Absolutely. They'd be crying for weeks after the Series 2 finale. FEELS