Like beauty, whether or not something is funny is very much in the eye of the beholder. Some will find the sight of someone slipping on a banana skin funny. Others will find humour in the behaviour of politicians, or the foibles of human behaviour.
When bloggers are writing about things they find funny, they might be writing about their favourite joke, their favourite funny story, a funny television show or website.
"Funny" most commonly means causing laughter or amusement, but it can also mean peculiar, odd or unexpected.