Yu-Gi-Oh Abridged Wiki

Hair Guy is the most seen of Pegasus’s henchmen. He is also known as "The Nameless Henchman" in the series, for writing purposes his original dubbed name is used. He is based on Kemo from the Yu-Gi-Oh! anime.

Kemo has a tendency to yell "Attention Duelists!" followed by a remark about his hair every time he starts a conversation, even if he's not addressing duelists. When asked why he does this, he replied angrily that it's simply what he does.

Another of Kemo's traits is referring to his hair in some form or another, usually related to what he is actually doing. For example, in Episode 6, when attacking a duelist he shouts, "Attention Duelists! My hair is assaulting you!" In the same episode, he also claimed that his hair gives him the power to defy gravity. In another, he told Kaiba, "My hair is definitely not leading you into a trap!" When Kaiba threatened to shave it off, Kemo set off an alarm and claimed it was for threatening his hair. His hair apparently also has a crush on Mai Valentine.

Kemo has apparently taken child-grabbing classes, and on occasion he refers to them. He has said that his child-grabbing classes were a waste of money, although at other times claims that they've paid off. He returns in Yu-Gi-Oh: The Other Abridged Movie, where he is once again using what he learned from his "child-grabbing" classes to kidnap Gary, only to be stopped by Joey. This apparently arouses his hair.

After Pegasus's defeat, Kemo is then seen working for the Big Five in episode 21. However, he is written out of the show at the end of episode 21, where he called his mother (addressing her with "Attention Mother!") and asked to move in with her. 

Kemo without his hair.

For reasons he himself doesn't really know, he's working for Kaiba instead of Pegasus and he lost his hair, though he still makes references to it. He also appears in the Star Trek: The Next Generation Opening of Episode 32 as Commander Worf, being attacked by the Borg and crying out about his hair.

He is also the long lost father of Tristan due to the fact that they have a similar hair style as well as the fact that they both refer to their "hair" and "voice" as people. 

In Episode 50, it is shown that he has a brother named "Mullet Guy." His brother also shares the trait of saying "Attention duelists." He tells Kemo that his mullet thinks child grabbing classes are a waste of time. This pisses Kemo off and may have been what prompted him to do it since at the time it was just a consideration.

In Episode 80, it's revealed that his hair doubles as an antenna, as he presents a recap in the style of the "Previously on Yu-Gi-Oh!" recaps.

According to LittleKuriboh's LiveJournal, he was emailed by one of the people running the UK tournament*, asking him to come and announce the tournament. They said that they really needed someone capable of saying "Attention Duelists!".

*Nationals perhaps?