He then claimed to be Emperor of the Universe and decided that Time and Space obeyed his rules and he could change them whenever he wanted, making everyone confused. The Weeping Angels and the TARDIS suffered most from this.
He was nicknamed Emperor Wassabe because he used to be cool and now he is not. Kids made fun of him because he tried to make things funny when they weren't. For example, he tried to make everyone think that the Doctor would stand around bumbling and making jokes when there's a serious problem. The Doctor did not like him for this.
That's not all. He tried to reveal the Doctor's real name to everyone and was jailed for a year for doing so. However, even this did not stop his spree. He tried to incite that there was a romance between the Doctor and his companions, and even suggested that he had a wife as well.
In the end, the Daleks got so sick of his fooling around that they Exterminated him. His corpse is now on display in the Dalek Asylum, alongside Awkward Rainbow Flower Power Dalek.