/Stupid Feeling

In this thread just post something that made you feel stupid.
Example: For me, posting on like 40 diffrent year old topics(I did get warned for it)

At one time I used to think dogs were better than cats.


I changed my mine within days.

Most of the times I feel stupid when I try to teach how to use an alarm system for a new client, I explain everythng really detailed and 90% of the cases they say I didn't understand, I think i'm just bad teaching stuff from my work

I feel stupid when:

1) my mind is somewhere else and I get a simple problem/question wrong
2) I think somebody's waving at me, so I wave, but it's actually a person behind me
3) I post a letter guess in a solution hangman round

Made me feel pretty stupid.