A name givin to a male who is a failure with the opposite sex.They can't carry on a conversation with a female for more than a few secounds without the girl walking away in disgust/fear or slapping the guy in the face. Typically they have a odd fashion sense and where shirts with "funny" sayings on them that are just plain uncool. The guy will say the most ungodly awful things to the girl. They typically go for girls way out of there leauge and they almost always don't know there is anything wrong with there behavior till a friend tells them.
A example of a theseth saying a werid thing
a theseth: Hi how are you?
girl: Not too good, I got a bad sunburn
a theseth: Sunburns are not so bad there fun to pick at.
(girl walks away)