This book by Jonas Jonasson and translated from the original Swedish is oftentimes silly and clearly intended to be fantastical, but extremely funny.
The title character, Allan Karlsson, does just as the title suggests in the book's first chapter. Immediately prior to the hundredth birthday party planned for him at his nursing home, he decides he's had enough of the place's strict rules (particularly the one prohibiting vodka), climbs out the window and runs away. The remainder of the book alternates between telling the story of the 6 weeks following his escape and his earlier life adventures. Both parts are equally entertaining.
When he first escapes he shuffles to the bus station and buys a ticket on the first bus out - he didn't care where it was going. Before he leaves he manages to steal a suitcase full of cash from a petty drug dealer which leads to endless comical encounters with that dealer and his accomplices as they try to recover the cash. And no matter what happens Allan comes out ahead.
This is after a life of globe trotting meeting world leaders from Truman, Johnson and Nixon to Franco, Stalin, Mao, Kim Jung Il and de Gaulle. Though he spends time in an asylum in Sweden, a prison in Iran, the Gulag and traversing the Himalayas by foot, he's always happy if he's offered a good meal and plenty of vodka. Fervently disinterested in politics he manages to get on the inside of almost all major political events of his lifetime - and to provide his explosives expertise to whichever side offers him the best meals and drinks at the time.
It's really worth suspending your disbelief for the sheer entertainment value of this book.