Nickelodeon's first movie turned 20 last summer, and its star, Michelle Trachtenberg, is making us feel archaic with Harriet the Spy content. On Thursday (March 23), she posted an unbelievably precious #TBT that belongs in the Smithsonian. [Note: Nickelodeon and MTV News are both owned by Viacom.]

An October 1995 behind-the-scenes pic from her first movie depicts a 10-year-old Trachtenberg posing with costar Gregory Smith, who played her BFF turned rival turned BFF again, Simon "Sport" Rocque. Trachtenberg explains how the shirt she's wearing was her "lucky" t-shirt from the Gap, and was what she wore during her Harriet audition — and then never wanted to take off.

Harriet the Spy had it all: a girl who got shit done, Rosie O'Donnell being the world's best nanny, and a seriously epic paint fight scene (complete with the bitch slap heard round the world). Oh, golly!