Joke

All Past Umno Leaders Quit Party Except One --> source from Malaysiakini

Four of Umno past leaders - Onn Jaffar, Tunku Abdul Rahman, Hussein Onn and Mahathir - eventually left the party. The only exception was Abdul Razak, who died in office.

There are 2 jokes here.
The first one is obvious.
The second one is...the party is so lao ya that it becomes a big joke with its joker leaders.

No Offense... Its just a joke.