I received this call while working for support for a cable equipment provider. Customer was complaining about one channel not coming out. After 20 minutes of exhaustive troubleshooting. This guy was actually nice and I just felt bad for him after.
Me: Ok sir, I will be honest I am almost out of ideas. You are sure everything is setup properly and all cables are plugged in?
Client: Yup I did it myself!
Me: Ok, I have one more test for you. Under output settings we have an option to turn on colour bars. I would like you to turn that on.
Client: Done, and still nothing! What does that mean?! (said happily, obviously amused he stumped the support guy)
Me: (tired and slightly frustrated with my skills) Means one of two things, either the card is busted or you have not plugged it in.
Client: (Still amused with himself) Ok for you I will doubl.... would you look at that, I musta missed that cable.
Me: *Bashing head into desk with microphone on mute*(unmuting)Ok great so just plug that in and we should be good to go.
Client: (Noticeable embarrassed, but trying to hold up face) well... thank you for all your help, and uh I should be good now.
Me: Have a great day (checking job postings online)