Albert Camus' The Stranger is not often read for its comedy value however Meursault the hero and narrator likes a joke. He tells us that Salamano's dog manages to wriggle out of his collar and escape while his owner was watching "the Escape king"  and he tells us of Raymond's silly hat that makes Marie laugh . Marie's laughter is in fact what attracts Meursault to her and he makes 18 separate references to her laughing or smiling. Patrice Mersault, hero of A Happy Death (a kind of pre-run for The Stranger) is very attracted to mouths, 'lips' are mentioned several times in a sexual context but this is the subject for a future post. Meursault's humour is also dark, like the humour of many writers of 'the absurd' - check out the work of Daniil Kharms. A example of this is his claim to have not noticed the Arab nurse is missing a nose. After describing, in detail, the facial features of the old caretaker at the care home, Meursault claims to have not noticed that "Where her nose should have been the bandage was flat" 
One of Meursault's hobbies, he tells us, is to keep "an old exercise book where I put things that amuse me in the papers."  In chapter two he cuts out an advertisement for Kruschen Salts to go in this book. A quick internet search reveals the kind of advertisments this laxative company favoured. The suggestion in all these ads is that an productive session on the toilet is a cure for all ills. These ills range from things like rheumatism and fatigue to being overweight - all are cured, the last line of the advertising copy usually reveals, by a regular daily you-know-what. The accompanying pictures are always of men and women smiling gleefully because they go to the toilet regularly or frowning, gloomy individuals who don't. My personal favourite is a man who isn't getting on well at work - until the laxatives take effect - and he gets a pay rise.
How does knowing Meursault finds these advertisments amusing help us understand him as a character?
Often the playful side of this character is forgotten, the fact that he plays with Marie in the water and runs exuberantly after the lorry with his friend Emmanuel, who ends up "laughing so hard he could hardly breathe"  He plays pool with Raymond and enjoys the friendliness he feels directed towards him. 
How and why does Meursault find advertisments for laxatives amusing? These ads do as much as they can to hide the reality of the product they're selling. For him to find them funny, he'd need to reflect on them a while rather than simply glance over them in the newspaper. Some have claimed that his focus on the Kruschen Salts is a indication of his interest in the trivial (these commentators also point to his mentioning the soggy towel in the bathroom at the office). However, Meursault doesn't not claim that he finds the towel amusing (he's annoyed, like I would be, because it's soggy) but he does explicitly say he finds these advertisements amusing. If amusement is an emotion (Robert A. Sharpe offers 7 reasons why it is in an article for The Journal of Value Inquiry ) then Meursault experiences this emotion - a problem for those commentators on The Stranger who argue that he is incapable of emotion.
Below are some advertisement for Kruschen Salts that must be similar to the ones Meursault would have read. I'll post the happy laxative users first.
Now the grumpy people who would benefit from a laxative
Finally, a non-Kruschen ad that Meursault might think worth putting in his exercise book
You don't want to stand too close to Laxative Merry-Go-Round
[Text by Simon Lea]