My SIL joined us for Christmas Day. She wanted a dairy and gluten free dinner, which we sorted. Then we opened presents. She sulked about what she was given, then abruptly left, telling MIL and FIL that they'd bought her rubbish (she was given really nice stuff). I would have expected this from our little one, but SIL is 40.
On the subject of random crap, SIL gave me an absurd present (think something as bad as a roll of sellotape), with which I of course pretended to be delighted.
I find her such a pain. She holds the entire family hostage with the threat of an emotional outburst, and few people in the family seem capable of calling her out on her BS. Because she's extended family, I bite my tongue, but AIBU to want to call her out? She completely ruined the vibe for the rest of the day.