For me, I noticed I seem to say this most when I've ordered and eaten the perfect bacon, egg and cheese sandwich. If the person making it gets it right, it's like WOW. I've noticed that this is the one thing I consistantly say this over.
Not looking for "wow that was a good meal", this is a bit different. What I am looking for is like being in a state of mini Nirvana.
p.s. just right for the breakfast sandwich for me is, kaiser roll toasted, egg over easy, bacon extra crispy, mayo, and pepper. Today's was just SO good.