The only "humorous" ideas I laugh at are the ones that lack continuous engagement.
If there is a reason to believe that new content will be continually created/crowd-sourced then it is a solid business model.. for example peopleofwalmart
However, I know someone who pitched "fartmap" idea - a global heatmap of farts.
you or your friend farts=> you update the geolocation and the intensity on the map and guess what you can see farts happening in almost real time.
It may be disgusting to some but I agree that there is a small market which will find it funny too.
The only problem I saw was that I do not expect people to come back after a few uses, it is not that engaging a content.