Try Another Hole T-Shirt
"If I had another hole, I would have had Internet access." - Margaret Cho, Notorious C.H.O.
The nice thing about computer ports is that there are only so many wrong options, so eventually the user's got to get it right. Unfortunately, the "getting it right" part doesn't usually happen until after they call you. We feel your pain.
On the list of computer problems that tech support has to deal with every day, things not plugged up correctly ranks right up at the top. From not plugged in at all to plugged into a hole that's completely inappropriate, problems with holes seem to befuddle many users. The cables and ports can even be color coded, and the user will plug it up wrong, like some sort of artistic expression. ("I thought the blue and the green went together nicely.")
We've been there. We feel your pain. Encourage your users to self-service with this friendly suggestion. Or wear it to a bar for the double entendre value. This shirt proves you're geeky and funny. No better combination, in our not-so-humble opinions.
Try Another Hole printed in white with a series of ports beneath on a blue dusk 100% cotton t-shirt.