Nalding
Adding an event to your calendar without letting them know. Like you're sneaking it in like a thief in the night.
I added your meeting to your calendar without telling you. Now you think you're getting a promotion, but you're just getting more work.
You added my birthday to your calendar but forgot to invite me. So I showed up, and I was all like, 'Surprise? I was expecting a surprise, but this was a trap.'
She added my ex's birthday to my calendar. Now I have to remember that he's still alive.