Was named after a good friend who was your typical, squinty eyed, slow talking stoner with a cannabis card. It's very useful as a code name, seeing as it can easily be mistaken for the name of a friend if parents/teachers/higher forms of authority are present.
The phrase "going to tanner's house" is also useful when talking about going out to get stoned.
"I got so tannered last night, I can't remember a thing"
"Hey man, wanna go over to tanner's house?"