Funniest memory of a holiday I have is with family friends who had never ever gone away on a holiday ever before and for some reason chose to grace us as holiday companions. I don't know how we got sucked into it too much drink, but we landed up in this small Austrian chalet in early spring with two small children (DD 3, their DD 6).
Friend tells us to go get some food from nearby tiny village while she unpacks, long list with exact prices and all british brands noted. When we get back, with a fairly different set of things, she has stripped all the rooms of all cloth, so blankets, curtains etc and washed them by hand
So we're stuck in snowy hillside with thoroughly disinfected, dripping wet blankets. Yes she was a bit of a clean freak always, but still. We had to bring out those shiny emergency thermal blankets from the car.
Then she lets us know she is agoraphobic, so any walks, treks etc are out of the question. Bear in mind this is a tiny chalet on an effing mountain, nothing else to do all around. We ask why she wanted to come here, she says another friend came for skiing. Does she want to ski? Of course not!
So we start going away by ourselves, but her DD wants to come. She won't let her come alone, so she will come with us. Her DH seems to be her second child, he doesn't get a vote. Every time we walk too fast, climb anything, go near anything, she screams in fear. My DD picked a flower, I thought she would faint then and there.
At every meal, she talks of food poisoning with foreign food and moans about TV shows we are missing.
She comes out one morning and declares, This place has too much snow, it's not natural. Yep, snow is not natural for a mountain in the Alps, got you 
Her DD scratched her elbow and she nearly got mountain rescue called in. Probably thought I was the most careless mother ever because my DD sneezed one day and I didn't send her straight to bed with Calpol (not exaggerating at all, one sneeze equals bed rest in their house).
It was infuriating at first, then it became so ridiculous we started enjoying it. DH and I played a guessing game about her reactions all the time, and generally tuned her out.
Haven't tried going anywhere with them since.