I usually smile [at them] and give some sort of guffaw, but inside, I secretly want to hold them under water. Just for a minute or so. Just until they panic a little.
(I disagree with the title-- YOU, WE should be the one to say those things to other parents. Why make them (us!) think it to ourselves?)
http://www.stevewiens.com/2013/03/12/to-parents-of-small-children-let-me-be-the-one-who-says-it-out-loud/