Say something nice; make someone feel bad.
Miss Manners would have thought this a difficult combination to pull off. Insults are easy and, she regrets to say, plentiful. There is general agreement about what constitutes a negative attribute, and the insulter has only to name it. As reinforcement, there is the sneer with which insults are delivered.
But compliments that leave their targets miffed and their givers bewildered are also plentiful. They just require a bit more thoughtlessness.
Guessing about the situation being admired is almost a sure method:
"I see you're pregnant -- congratulations!"
"What an adorable child. You must be the proud grandfather."
"Is that your girlfriend?"
"I bet you're the smartest one in your class."
"You must be making a fortune to afford that."
Almost as effective is asking:
"Your hair is such a beautiful color. Is it dyed?"
"Where'd you get that darling baby? He doesn't look anything like you."
"Wow, your performance was amazing. Do they check for steroids?"
"I bet all the boys are after you -- so how come you're not married yet?"