This one is sort of self explanatory but in honor of the topic, I will explain it anyway.
Guy who explains things unnecessarily is everywhere, you could say he is everyman. To be fair, some men know their limits and eventually shut the hell up. GWETU is a close cousin to street smarts guy but is an evolved and perhaps more successful form. For all intents and purposes GEWTU might even be your own father so here's how to tell. For the rest of this blog I will refer to GWETU as "G".
"G" fancies himself an intellectual but he lacks what true intellectuals possess and that is important, useful information or in depth knowledge on any topic. "G" does however have plenty of information you already know/don't care about and he is particularly interested in proving his knowledge with or without your consent.
Me: Hey "G" can you pass me that DVD?
G: DVD eh, so you want the ol' digital versatile disc or the ol' digital video disc.
G: Ya know, before DVD's we used to use VHS tapes.
Me: VHS huh, do you know what that stands for?
G: Nope, but, they did become the predominant form of taped movies edging out betamax back in the day. Heck, some believe it was a superior device, god bless advertisin'. But that was before they had all this new technology. Sheese, you can't even buy a regular light bulb anymore.
Me: Tell me about it.
G: Hey, didja know that the double yew besides the number on a light bulb means watts?
Me: Um, sure.
G: Hmm... all of this chatter has made me hungry could you make me a sammich?
Me: Sure what kind?
G: How's bout peanut butter.
G: You gotta be careful when you make a peanut butter sammich. You gotta spread the PB smoothly so that both pieces have an even coat, not too thick, not too thin. Say, did you know contrary to popular belief that peanuts don't grow in trees? in fact they grow from a plant underground, thus the name Planters Peanuts.
This exchange could go on for hours. No indication of boredom, disinterest or annoyance can combat "G" when he is on a roll. You only hope in dismantling the conversation is cutting "G" off before he somehow integrates the thing he is explaining into a past life experience or a memory about a particular friend/family member with whom he had a bad experience. If this happens then you better get some popcorn because "G" is libel to continue explaining things unnecessarily until one of you falls asleep.