The best kinds are insults disguised as compliments.

“I hope your day is as pleasant as you are.”

“I can’t tell you how much I enjoyed your presentation.”

“You never cease to amaze me.”

“If we were sat on a bench together and someone came up and said ‘One of you two is an idiot’, I wouldn’t think they were talking about me because I don’t take offense easily”.

“I am sure that with enough determination, you can make it to the top of the bell curve.”