surprise discovery past

I'm going out for lunch today, which means missing out on Nepali lesson. Shame! And we've been learning a new tense as well - the surprise discovery past tense. This is a tense specifically for when you discover something that happened in the past, but you've only just found out about it. For example, "Oh, look, the dog did a poo behind the sofa yesterday!" or "Oh, you have syphilis, you must have had an affair!"

I'm sure it will come in very handy when I am taking taxis or telling the housekeeper how Hubby would like his shirts ironed.