A male colleague once accidentally ended a call with me 'love you, bye'.
Yep, nearly done that several times too: to someone at the bank call centre once, and random other people, usually if, we've chatted for a while and they've been especially helpful and I'm feeling well disposed towards them.
Fortunately, I've always managed to stop myself in time.
Many years ago, long before the internet when people still wrote letters, my mother sent a letter to the specialist treating my brother with an ongoing, serious illness.
It was a long letter outlining symptoms and problems. She signed it: 'yours affectionately mother'; it was a long time ago and my mother was very old fashioned and formal.
Poor woman was mortified when she realised what she'd done immediately after she'd put it in the letter box.
A rather panicky phone call from her to the specialist's secretary ensued and all was explained but I think she blushed about that for months.