Stan Pines

Mabel and Dipper were with their "Grunkle" Stan Pines in the Mystery Shack when the Doctor's TARDIS clipped its roof and flew through its interior, following the Tenth Doctor telling Rose Tyler that they would be travelling "further than [they'd] ever gone before". His niece and nephew speechless as to what they had just seen, Stan asked them if they wanted to see what was on television. (TV: Untitled)

Behind the scenes
Stan Pines originates from the Gravity Falls series. Archival audio of his voice actor,, is used during his appearance.