What experience was the most different from what you expected?

My first orgasm from a woman. OK, I'd had them from guys before but I was not prepared for the intensity and length of what Laura did for me...

In high school I missed my school bus. I had to take the Art bus to school. I missed two periods, i went on to the third.

I didn't expect my father to come home from the hospital at about 2045h on Thursday, 24 Sep. 1964 & almost fall through the front door, muttering "No!", indicating that my mother had died.  That's still the most unreal experience I've ever had.      

Being abducted by space aliens

Sex for the first time. It was a complete disappointment.

coronavirus outbreak

Meeting the well-known mother of a friend of mine. I didn't expect her to be so down to earth.