Meme got me thinking of a friend who got into flat roofing, on one job he told me about a huge puddle of water around a drain. His instinct was to just pull the crap out of the drain and let the water flow out.

Tells me that his bost freaked out because with the weight of the water dropping into the pipe, that it can create huge pressures with the air trying to flow up and risks the pipe bursting which becomes a contractor paid fix.

The proper approach was to open it just a little and let it drain, might be slower, but safer.