Kitchen sink experiment simulates exotic white holes : When water hits the bottom of a sink, it flows outwards in all directions. At a certain distance from the point where the water hits the sink, the outgoing liquid rapidly decelerates and piles up before continuing its outward flow, creating a ring-like ridge.
Physicists have previously suspected that any ripples that might arise beyond the ridge and travel towards it should not be able to get past the ridge. This is because at the ridge the water flows outwards at the maximum speed that ripples could travel inwards, so the ripples would make no forward progress, like a runner on a treadmill. This makes the ridge behave like a white hole event horizon.