What would be an example of funny or general business topics for a five minute presentation to a very diverse audience?

It is always best to determine your speech topic based on your audience.  If you have a very general audience, try to match your topic to the occasion instead.  For example, if the audience is mixed but it is a graduation, then you base your speech on celebrating accomplishment, moving on, or success.  These are typical graduation topics. 

Making a humorous speech can be a big hit.  However, you will want to plan carefully.  Make sure that your jokes are tasteful and not at anyone’s expense.  Do not try to be funny by making fun of someone else, in other words.  This could backfire.  When trying to be funny with a wide audience, you have to be very careful.  Make sure you are not being bitter or vicious. 

The best way to make a speech appeal to a wide audience is to plan it around a theme that will appeal to the widest number of people, and then inject some humor where possible.  In other words, rather than trying to plan a comedy routine, write a meaningful speech and include some jokes.