By chance, is your TV a late model? Something that has access to the “internet of things?”
Anyway, my guesses are 1) merry pranksters; 2) someone testing a genuine message that is going out the wrong way (testing on a signal/channel someone thinks is not in use); 3) a genuine message being sent out and somehow your TV is sensitive to its reception. (Like a closed-circuit signal that is somehow being broadcast that your TV is able to pick up.)
I’m not a broadcast nor electronics engineer, so sorry to those who are for mangling or conflating terms or concepts.
It's a so-called smartTV, but not an "IOT" tv. It's a 3D TV made four years or so ago by Panasonic. It has WIFI and Ethernet connectivity, but currently only the ethernet is activated for network connections. Except for the WIFI, all of your examples are possibilities.