Phil of the Future, Disney Channel (reruns on Disney XD)
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Phil Diffy is from the year 2121, and he and his parents, Lloyd and Barbara, and his little sister Pim, were on vacation in the past, but somehow got stranded in our time. So they have to try to live a normal life, while hiding their origins from people. Oh, and a caveman apparently stowed away in the Diffys' time machine in the prehistoric past and wound up in the present, with them. They call him Curtis. He causes some comical trouble, as he's kind of hard to hide and keep under control, but eventually he starts to become at least a bit more civilized.
Phil's best friend in the present is Keely Teslow (who we like). She's the only one who knows the truth about the Diffys. The vice principal at Phil and Keely's high school (H.G. Wells, a nicely ironic name for the school) is Neil Hackett, who knows there's something strange about the Diffys and is often trying to find proof of... whatever their secret is. (He's played by the same guy as Curtis the Caveman, though I doubt I ever would've been able to tell if I hadn't read that fact online.)
Phil seems to be the most normal one in his family, and also seems to enjoy the time he's stuck in well enough. There's not much I can say about his parents, but Pim is... an endearing little imp, who considers herself above everyone, especially the primitive people of the 21st century, and would love to take over the world. There's a girl she knows named Debbie Berwick who's annoyingly prissy and stuff, and Pim can't stand her, but Debbie thinks they're friends. (Debbie is played by Kay Panabaker, who also played Nikki on Summerland.)
Of course, the Diffys have alot of nifty gadgets from the future that do all sorts of, you know, cool, futuristic things. Most notable among these are the multi-purpose "wizard" and a vehicle called a "skyak." I dunno what else to say right now. It's a silly show, not great, but I enjoyed it well enough.