Don't know if it's been mentioned here before, but the 2004 movie Raising Genius features a very, very brief foot tickle of Wendy Malick, about halfway through the movie. Wendy Malick is lying on the bed as her husband, Stephen Root, paints her toenails. He then allows his fingertips to briefly trail along her arch (trying to entice her into sex). Malick displays a brief, but apparently genuine, ticklish reaction (although it's in a reverse-angle reaction shot, so you could question whether her response is genuine -- I imagine it's real because I don't believe she's all that good an actress). The movie is on the Showtime family of channels this month (next airing Friday, 8/12, 9:45 am EDT, but the program guide on Showtime's website lists at least nine more airings).