Some highlights from HN comments:
Cobweb antenna looks like it could be disguised in an umbrella on the table or something. Just for a nice-looking design if not anything nefarious. In both cases, the electronics can be hidden unless people look closely. Owner tells them about it. Now, they had two things to enjoy that day.
Sea Water Antenna
Trips me out how you hear the audio right after water starts shooting through it.
Two years ago, /r/amateurradio held a bedspring challenge which started as an off-hand comment about what could and could not be used as an effective antenna.