I am very fond of my SIL, but something that drives me utterly nuts is that she will turn up, and quietly whack the thermostat up to a temperature that would cook the turkey even if it never made it to the oven. Anyone in the kitchen gets absolutely baked, because it's hotter in there already, and then she will open some windows 'for the fresh air'.
(She is East German and I think the combination of fierce central heating and open windows is a hangover from Soviet times. Or so I've heard tell. I try to remember this and forgive her, while I am melting into a hot red puddle on the floor ...).
My dad is, unfortunately, brilliant at comments/contributions that make you feel your house is a hovel and everything in it is cobbled together from what you foraged from the local tip.
'Ah, hello, I see you've lit the candles, laid the table and you're about to serve food ... I'll just stack these three huge suitcases in the corner of the room. We've brought our own duvets from home of course.'
'Did you notice you've got a wobbly post by the gate? Well, I backed into it and it was definitely wobbly. I'll just show you the problem now, while your oven timer is ringing.'
<turns up in the kitchen with some unidentifiable object and an expression of doom> 'I found this in the attic and it looks like a worry. There might be dry rot. I'll need half an hour to look on google and find out what to do, I'm afraid.'
'I've just gone online and ordered you some proper side plates. We can use saucers for now, of course. What do you mean, you already own side plates and hadn't put them out because I interrupted you with the gate post?'
'I've smashed a wine glass! It must be a defective one! Never mind, you buy what you can afford.'
<and breathe>