'Paul walks funny.'
'Like a chicken on a bicycle.'
To my nine-year old and his friend that is hilarious. To me, it's not, though it is funny watching them laugh at their silly and occasionally humourous jokes.
Getting comedy right is one of the most difficult parts of writing. As the above example shows, what is funny to one person isn't funny to another. What amuses one age group, will not amuse another. Add to the mix, culture, background, fears and phobias and many other things and humour becomes even harder to get right.
Slapstick and bawdy humour are about the only types that travel well, but even that is not assured.
Having done stand-up comedy in the past and written some (awful) comedy material, I have come face to face with this reality.
So if you're planning to write comedy, the best idea is to make it fairly general and cross-cultural. A good start to understanding humour in writing would be Terry Pratchett or Douglas Adams. They may not leave you in hysterics, but at least you'll get an understanding of how 'general' humour has to be in order to travel well. Or you could just write humour for a niche audience.