Possible Humiliation

A friend of mine recently admitted to me that whenever she is at another person’s house she takes a precaution in the bathroom in order to save herself from possible humiliation.
Before she uses the toilet, she gives it first a test flush. She explained that the very idea of plugging or overflowing the toilet at another’s house is so unbelievably mortifying that she takes this necessary step in order to completely remove the possibility of that happening.
I thought “OMG, does everyone do this? Because causing a toilet to overflow is soooo crazy embarrassing!! Now I am going to have to do this every time too”. But what if the other people in the house hear you flush twice! Will they think you just did some business that required a double flush, because THAT is embarrassing too!
Then it made me think of my sister. She runs the tap while she’s peeing so no one will hear the pee hitting the water sound (even though every time I hear the tap running I giggle and I totally know she’s peeing and trying to hide it). So now I have to run the water and flush the toilet twice in order to save myself from possible humiliation.
Why why why did I have to think about this????!! I used to save so much more water!