My MIL sends a birthday card to my husband in the post. Then when we visit later that week gives him a second birthday card along with his presents.
She buys her dog a Christmas present... and wraps it up.
After Christmas dinner serves cold leftover meat with hot veg. It's not the craziest thing but it winds me up because I hate cold food.
Honestly my husband would have more strange habits from my family! Contrary to previous posts, I despise living room side lights because the dimness gives me a headache. My parents absolutely refuse to use the single big light, instead turning on four smaller, duller lights. I cannot visit them after dark.
Also, as soon as the sun nears the horizon the blinds in every room MUST be lowered. The reason being it would be terrible if (gasp) the neighbours could look in and see them sitting on the sofa.
As previous posters, tea and coffee time is sacred and always must be adhered to.
They also cut boxes down to size as things get used. So a nearly empty box of waffles is sliced in half to save freezer space.
NO ONE is able to load the dishwasher except my mother. If you attempt it, she will come in after you and rearrange it. Also, there must be not a shred of wasted space in the dishwasher - every square centimetre must be filled with something dirty - before she can contemplate turning it on. And she cuts the dishwasher tablets in half because that's all you need.
Dad gets changed every time he goes out to his "going out trousers", then back into his "at home" trousers upon return. Tbf my husband also does this, so I guess it's a man thing?
My grandparents will whisk dishes away and wash them up, even if you're not finished. Once I was using my knife to help my son cut his food (think he was very young at this point) and I set it down for a second. Went to pick it up again and it was gone.
And I have to tell on myself as well. I have a thing about my glasses: only I can move it. Husband learned very soon in our relationship to not carry my glass over to me. Once he touches it, I can no longer use it and half to get a fresh one. The other night he moved the table my glass was resting on and it did not go down well, but his defense was he didn't touch the glass. Mugs are absolutely fine to transport. (yes, he is a very longsuffering husband!)