The "Chroma crosstalk" activity in my NES and SGB ports of 240p Test Suite exploits this on NTSC TVs. (These are based on my earlier "tvpassfail" demo.) It puts the pixels in the order red-green-blue-red-green-blue, specially arranged to cause the signal to be high or low for most of the dot period. A few letters are drawn in large type with the phases shifted by 1 unit: green-blue-red-green-blue-red. Because the relative phase between the dot clock and the color burst is unpredictable at power up, it then increments all three colors through the rainbow. The user of an NTSC composite display can see the letters slowly fade in and out.
Without filter: With blargg's NTSC filter: