Isn’t that a classic too? As in your mouth runs off and your brain trails behind. Later you ask yourself wtf you just said.
I hate when that happens, especially during job interviews.
FiskFisk33 already answered it. It’s about speaking vs. writing/ using language.
On a serious note (and thereby killing the joke completely): doesn’t everyone know the situation where you can’t get the word out that may be very well in your head?